linux set date

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So we see that df gives some valuable information on the file systems,their mount points, their memory usage etc.

1. Display Information of all the File Systems

If the disk usage of all the file systems is required then use -a option:

$ df -aFilesystem 1K-blocks UsedAvailable Use% Mounted on/dev/sda1 132239776 6210892119311496 5% /proc 0 00 - /procsysfs 0 00 - /sysdevpts 0 00 - /dev/ptstmpfs 4021876 04021876 0% /dev/shmnone 0 0

0 - /proc/sys/fs/binfmt_misc/dev/sdb2 30969600 11774029278696 1% /home/oracle/dev/sdc1 576310180 71232546964104 1% /home/data

So we see that in the output, details of all the file systems and theirmemory usage is there.

2. Specify the Memory Block Size

If you see the output in point 1 above, the second column gives thememory of file system in memory blocks of 1k. df command providesan option through which we can change the size of memory block inthe output. Use option -B for this:

$ df -B 100


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Filesystem 100B-blocks UsedAvailable Use% Mounted on/dev/sda1 1354135307 635995351221749720 5% /

tmpfs 41184011 041184011 0% /dev/shm/dev/sdb2 317128704 1205658299813848 1% /home/oracle/dev/sdc1 5901416244 7294165600912425 1% /home/data

So you see that we specified a block size of 100 and in the output

(second column) block size of 100 is displayed.

3. Print Human Readable Sizes

We are used to reading the memory in terms of gigabytes, megabytes,etc as its easy to read and remember. df command also provides anoption -h to print the memory statistics in human readable format.

Option -h stands for human readable format. As shown in the output

below, G is used for gigabytes and M is used for megabytes.

$ df -hFilesystem Size Used Avail Use%Mounted on/dev/sda1 127G 6.0G 114G 5% /tmpfs 3.9G 0 3.9G 0%/dev/shm

/dev/sdb2 30G 115M 28G 1%/home/oracle/dev/sdc1 550G 70M 522G 1%/home/data

4. Display Grand Total in the Output

Till now we have seen that only disk usage statistics of individual filesystems is produced. If we want to display a grand total of every

column then we can use the total flag. Here is an example:


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$ df -h --totalFilesystem Size Used Avail Use%Mounted on/dev/sda1 127G 6.0G 114G 5% /

tmpfs 3.9G 0 3.9G 0%/dev/shm/dev/sdb2 30G 115M 28G 1%/home/oracle/dev/sdc1 550G 70M 522G 1%/home/datatotal 710G 6.2G 668G 1%

So we see that a new row total at the end of the output was produced.

5. List Inodes (Instead of Block Usage)

Till now we have seen that df prints the second column as totalmemory blocks. If information in terms of inode is desired then dfprovides an option -i for this.

$ df -i

Filesystem Inodes IUsed IFreeIUse% Mounted on/dev/sda1 8396800 65397 83314031% /tmpfs 1005469 1 10054681% /dev/shm/dev/sdb2 1966560 2517 19640431% /home/oracle

/dev/sdc1 36593664 11 365936531% /home/data

So we see that information in terms of inodes is displayed.

6. Print File System Type

If you wish to print the type of file system in the output, use option -T.

$ df -T


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Filesystem Type 1K-blocks UsedAvailable Use% Mounted on/dev/sda1 ext4 132239776 6210892119311496 5% /

tmpfs tmpfs 4021876 04021876 0% /dev/shm/dev/sdb2 ext2 30969600 11774029278696 1% /home/oracle/dev/sdc1 ext2 576310180 71232546964104 1% /home/data

In the above output, we can see all the file systems along with their

type is displayed. Apart from using df -T to identify file system, thereare 4 other methods to identify the file system types.

7. Include/Exclude Certain File System Type

You can also display file systems that belongs to certain type. Forexample, the following command displays only ext2 file systems.types.

$ df -t ext2Filesystem 1K-blocks UsedAvailable Use% Mounted on/dev/sdb2 30969600 11774029278696 1% /home/oracle/dev/sdc1 576310180 71232546964104 1% /home/data

Mount Command

The syntax is as follows:

mount /dev/XYZN /mount/point

WARNING! The mount commands require root userprivilege or the corresponding fine-grained privilege,
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unless the file system is defined as "user mountable" in

the /etc/fstab file.

Examples

Mount /dev/sda5 (Linux partition) in /data directory:

mkdir /datamount /dev/sda5 /datadf -Hls /datacd/data

Mount /dev/aacd0s1g (FreeBSD UNIX partition) in /salesdatadirectory:

mkdir /salesdatadf -H

mount /dev/aacd0s1g /salesdatals /salesdatacd/salesdata

Mount /dev/dsk/c1t4d0s0 under Solaris UNIX at /data2, enter:

mkdir /data2mount /dev/dsk/c1t4d0s0 /data2

To remove mount point run:

umount /salesdata

To mount all file systems listed in /etc/fstab, enter:

mount -a

Further readings:

man mount

du


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You need use the command line utility called du to displays the filesystem block usage. In this example find out /tmp dir disk usagestatistics (open the terminal and type the following command):$ du /tmp

Sample outputs:

4 /tmp/vmware-root8 /tmp/pulse-xc7xdoM9vB2K4 /tmp/.X11-unix4 /tmp/keyring-7qXGnQ4 /tmp/.exchange-vivek4 /tmp/.winbindd

8 /tmp/plugtmp4 /tmp/virtual-vivek.C81Sd04 /tmp/VMwareDnD4 /tmp/ssh-mhNeIv19614 /tmp/.ICE-unix8 /tmp/orbit-vivek4 /tmp/.esd-100031644 /tmp

The -h option provides "Human-readable" outpu i.e. you will see it inByte, Kilobyte, Megabyte, Gigabyte, Terabyte and Petabyte:$ du -h /tmp

Sample outputs:

4.0K /tmp/vmware-root8.0K /tmp/pulse-xc7xdoM9vB2K4.0K /tmp/.X11-unix

4.0K /tmp/keyring-7qXGnQ4.0K /tmp/.exchange-vivek4.0K /tmp/.winbindd8.0K /tmp/plugtmp4.0K /tmp/virtual-vivek.C81Sd04.0K /tmp/VMwareDnD4.0K /tmp/ssh-mhNeIv19614.0K /tmp/.ICE-unix

8.0K /tmp/orbit-vivek4.0K /tmp/.esd-1000
http://www.cyberciti.biz/tips/linux-unix-du-command-examples.htmlhttp://www.cyberciti.biz/tips/linux-unix-du-command-examples.html


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33M /tmp

df: Display Free Disk Space

To show statistics about the amount of free disk space on the specifiedfile system or on the file system of which file is a part use the dfcommand as follows:$ df$ df -h

Sample outputs:

Filesystem Size Used Avail CapacityMounted on/dev/wd0a 938M 43.0M 848M 5% //dev/wd0e 817M 2.0K 776M0% /home/dev/wd0d 2.9G 573M 2.2G20% /usr

GUI Tools: Disk Usage Analyzer (Gnome Version)

Disk Usage Analyzer is a graphical, menu-driven application to analyzedisk usage in any UNIX / Linux / BSD Gnome desktop environment.Disk Usage Analyzer can easily scan either the whole filesystem tree,or a specific user-requested directory branch (local or remote). To startthis tool visit Gnome menu click on > Applications > Accessories >Select the Disk Usage AnalyzerAlternatively, you can start Disk Usage Analyzer from a terminalwindow, just type:

baobabbaobab /path/to/dirbaobab /home/vivek/mp3/

Sample outputs:


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Fig.01: GUI command to check UNIX / Linux / BSD disk space

Now, you can:

Start a full filesystem scan Select a specific local directory branch to scan Select a remote server and folder to scan etc

To start a full filesystem scan select Analyzer > Scan Filesystem fromthe menu, or press on the Scan Filesystem toolbar button. Disk UsageAnalyzer will display sizes in the directory tree as allocated space. This

means that the displayed sizes refer to the actual disk usage and not tothe apparent directory size. If you want to view the apparent file size,uncheck View > Allocated Space .
http://www.cyberciti.biz/faq/unix-disk-usage-command-examples/unix-disk-usage-analyzer/


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With that command, the -h option of the du command means "human

readable" (as in "show me MB and GB"), and the -s means "only

show summary information". It's important to note that this commandruns in real time, so for very large directories, it can be slow to returnyour results.

Show the size of only specified directories

Also, in that du command example, I knew that my current directoryjust contained the subdirectories shown, so I just issued that ducommand followed by the "*" wildcard character. If, in a morecomplicated world, I just wanted to see the size of a few subdirectories

in a directory that contained many more subdirectories, I could justspecify the directories of interest, like this:

$ du -hs Dir1 Dir2 Dir3

Linux du command output without the summary flag

As you can see, if I take the -s option off my du command I do indeed

get much lengthier output, like this:

$ du -h *

60K Burn-an-ISO376K BurnFolders/BurnFolders188K BurnFolders/images296K BurnFolders/images-orig1.2M BurnFolders

568K CreateAPodcast-1/CreateAPodcast1.1M CreateAPodcast-1/images/Original2.4M CreateAPodcast-1/images628K CreateAPodcast-1/L2HBackups28K CreateAPodcast-1/OldCSSFiles4.3M CreateAPodcast-1868K CreateAPodcast-2/CreateAPodcast740K CreateAPodcast-2/images

2.1M CreateAPodcast-23.8M CreateAPodcast-3/CreateAPodcast


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1.8M CreateAPodcast-3/images/bg-track720K CreateAPodcast-3/images/copying668K CreateAPodcast-3/images/external-track688K CreateAPodcast-3/images/joining

828K CreateAPodcast-3/images/new-track1.1M CreateAPodcast-3/images/splitting6.0M CreateAPodcast-3/images1.2M CreateAPodcast-3/images-orig/bg-track468K CreateAPodcast-3/images-orig/copying444K CreateAPodcast-3/images-orig/external-track464K CreateAPodcast-3/images-orig/joining

556K CreateAPodcast-3/images-orig/new-track768K CreateAPodcast-3/images-orig/splitting3.9M CreateAPodcast-3/images-orig16M CreateAPodcast-3200K Java-Mac-Jar-Bundler/images676K Java-Mac-Jar-Bundler/images copy808K Java-Mac-Jar-Bundler/images-old328K Java-Mac-Jar-Bundler/java-on-mac

2.5M Java-Mac-Jar-Bundler308K Java-on-Mac/images448K Java-on-Mac/java-on-mac1.3M Java-on-Mac

I'll guess that at least 95% of the time I use the -s option, because I'm

usually tracking down large directories, or I want to see the directorysize before I create an archive.

Chmod command Examples in UNIX and Linux

Now let's see some practical and frequently used example ofchmodcommand in UNIX


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chmod command Example 1: making read only file in Unix

In this example of chmod command in UNIX we will see how tomake a file read only by only providing read access to owner.

You can also give read access to group and others and keepwrite access for owner which we will see in subsequentexamples.

example@localhost~/testls-lrtstock_trading_systems-rwxrwxrwx 1 example Domain Users 0 Jul 1511:42 stock_trading_systems*

Here file stock_trading_systems has read, write and executepermission -rwxrwxrwx" for all

example@localhost~/testchmod400stock_trading_systems

400 means 100 000 000 means r-- --- --- i.e.read only for owner

example@localhost~/testls-lrtstock_trading_systems-r-------- 1 example Domain Users 0 Jul 1511:42 stock_trading_systems

Now file is read only and only owner can read it -r--------"

chmod command Example 2: change permissions only foruser, group or others.

In this example of chmod command we will see how to changefile permissions on user, group and others level. You can easily


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modify file permission for any of these classes. If you are usingtext format than u is user , o is other and g is group also ris read , w is write and x is execute. + means addingpermission and -is removing permission.

example@localhost~/testls-lrt chmod_examples-r-------- 1 example Domain Users 0 Jul 1511:42 chmod_examples

example@localhost~/testchmodu+wchmod_examples

example@localhost~/testls-lrt chmod_examples-rw------- 1 example Domain Users 0 Jul 1511:42 chmod_examples

Now lets change file permissions only for group by using chmodcommand

example@localhost~/testls-lrt chmod_examples-rw------- 1 example Domain Users 0 Jul 1511:42 chmod_examples

example@localhost~/testchmodg+wchmod_examples

example@localhost~/testls-lrt chmod_examples-rw--w---- 1 example Domain Users 0 Jul 1511:42 chmod_examples

In this chmod command example we will change permission onlyfor others class without affecting user and group class.

example@localhost~/testls-lrt chmod_examples-rw--w---- 1 example Domain Users 0 Jul 15


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11:42 chmod_examples

example@localhost~/testchmodo+wchmod_examples

example@localhost~/testls-lrt chmod_examples-rw--w--w- 1 example Domain Users 0 Jul 1511:42 chmod_examples

Chmod command Example 3: change file permissions for

all (user + group + others)In last unix chmod example we learn how to change permissionfor user, group and others individually but some time itsconvenient to change permissions for all instead of modifyingindividual permission for user, group and other.

If you are providing permission in text format than a is used forall while u is used for user.

example@localhost~/testls-lrtlinux_command.txt-rw--w--w- 1 example Domain Users 0 Jul 1511:42 linux_command.txt

example@localhost~/testchmoda+xlinux_command.txt

example@localhost~/testls-lrtlinux_command.txt-rwx-wx-wx 1 example Domain Users 0 Jul 1511:42 linux_command.txt*

Chmod command Example 4: Changing permissions innumeric format of chmod command


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Chmod command in UNIX and Linux allows modifyingpermissions not just on text format which is more readable butalso on numeric format where combination of permissions arerepresented in octal format e.g. 777 where first digit is for user,second is for group and 3rd is for others. Now if you write down1st digit in binary format it will be written as 111 on which 1st digitis for read permission, 2nd is for write and 3rd is for executepermission.

example@localhost~/testls-lrtunix_command.txt

-rw--w--w- 1 example Domain Users 0 Jul 1511:42 unix_command.txt

example@localhost~/testchmod777unix_command.txt

example@localhost~/testls-lrtunix_command.txt

-rwxrwxrwx 1 example Domain Users 0 Jul 1511:42 unix_command.txt*

Chmod command Example 5: How to remove filepermission using chmod command Unix

In this example of chmod command in UNIX we will see how toremove various permissions from files. You can easily removeread, write or execute permission from file using chmodcommand in both numeric and text format. Below examplesshows removal of execute permission represented by x in textformat.

example@localhost~/testls-lrtlinux_command.txt-rwx-wx-wx 1 example Domain Users 0 Jul 15

11:42 linux_command.txt*


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example@localhost~/testchmoda-xlinux_command.txt

example@localhost~/testls-lrt

linux_command.txt-rw--w--w- 1 example Domain Users 0 Jul 1511:42 linux_command.txt

Chmod command Example 6: changing permission fordirectory and subdirectory recursively in Unix

This is the most frequently used example of chmod command

where we want to provide permission to any directory and allcontents inside that directory including files and sub directories.By using R command option of chmod in Unix you can providepermissions recursively to any directory as shown in belowexample of chmod command.

example@localhost~/testls-lrttotal 8.0K-rwxrwxrwx 1 example Domain Users 0 Jul 1511:42 unix_command.txt*drwxr-xr-x+ 1 example Domain Users 0 Jul 1514:33 stocks/

example@localhost~/testchmod-R 777 stocks/

example@localhost~/testls-lrt

total 8.0K-rwxrwxrwx 1 example Domain Users 0 Jul 1511:42 unix_command.txt*drwxrwxrwx+ 1 example Domain Users 0 Jul 1514:33 stocks/

example@localhost~/testls-lrt stockstotal 0


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-rwxrwxrwx 1 example Domain Users 0 Jul 1514:33 online_stock_exchanges.txt*

Chmod command Example 7: How to remove read andwrite access from file for all

So far we have been seeing how to provide read, write andexecute permission to file and directory in UNIX and now we willsee opposite of that i.e. how to remove read, write and executeaccess. Its simple in text format because instead of + we aregoing to use -. Just like + used to add permission will be usedto remove permissions.

example@localhost~/testls-lrtstock_trading_systems-rwxrwxrwx 1 example Domain Users 0 Jul 1511:42 stock_trading_systems*

example@localhost~/testchmoda-wxstock_trading_systems

example@localhost~/testls-lrtstock_trading_systems-r--r--r-- 1 example Domain Users 0 Jul 1511:42 stock_trading_systems

Chmod command Example 8: setting execute permission

only on directories without touching files

Many times we just want to provide directory or subdirectoryexecute permission without modifying permissions on file just tomake those directories searchable. Until I know this command Iused to do this by finding all directory and then changing thereexecute permission but we have a better way to do it by usingchmod command in UNIX. You can use "X" (capital X) options to


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provide execute permission to only directories without touchingfiles. Lets see an example of chmod command for that:

example@localhost~/testls-lrttotal 8.0K-r--r--r-- 1 example Domain Users 0 Jul 1511:42 stock_trading_systemsdrw-rw-rw-+ 1 example Domain Users 0 Jul 1514:33 stocks/

example@localhost~/testchmoda+X *

example@localhost~/testls-lrttotal 8.0K-r--r--r-- 1 example Domain Users 0 Jul 1511:42 stock_trading_systemsdrwxrwxrwx+ 1 example Domain Users 0 Jul 1514:33 stocks/

Remember to use X (capital case) if you use x (small case) it willaffect all files and directories.

Chmod command Example 9: changing mutiple permissionfor a file or directory in Unix or Linux

You can change combination of user + groups or groups+ otherin one command to modify permissions of files and directory.

Below example of chmod command just doing same itsproviding execute permission for user and read, executepermission

example@localhost~/testls-lrttotal 8.0K-r--r--r-- 1 example Domain Users 0 Jul 1511:42 stock_trading_systems

drwxrwxrwx+ 1 example Domain Users 0 Jul 15


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14:33 stocks/

example@localhost~/testchmodu+x,g+xstock_trading_systems

example@localhost~/testls-lrtstock_trading_systems-r-xr-xr-- 1 example Domain Users 0 Jul 1511:42 stock_trading_systems*

Chmod command Example 10: How to copy permission

from one file to another in UnixThis is very interesting example of chmod command in UNIXwhich copies permission from one file to another. You can easilyreference source file and copy all permissions on that file todestination file as shown in following chmod example:

example@localhost~/testls-lrt future_trading-rwxrwxrwx 1 example Domain Users 0 Jul 1515:30 future_trading*

example@localhost~/testls-lrtstock_trading_systems-r--r--r-- 1 example Domain Users 0 Jul 1511:42 stock_trading_systems

example@localhost~/testchmod

--reference=stock_trading_systemsfuture_trading

example@localhost~/testls-lrt future_trading-r--r--r-- 1 example Domain Users 0 Jul 1515:30 future_trading


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These were some offrequently used example of chmodcommand in UNIX or Linux. Chmod command is as useful asUNIX find command or grep command and knowing how tochange file permissions is essential skill while working in UNIX.Please share if you have any other example of chmod commandwhich we should be aware of.

Read more: http://javarevisited.blogspot.com/2012/03/10-example-of-chmod-command-in-unix.html#ixzz1ybsKBzU0

sort [OPTION]... [FILE]...DESCRIPTION

Write sorted concatenation of all FILE(s) to standard output.

Ordering options:

Mandatory arguments to long options are mandatory for short options

too.-b, --ignore-leading-blanks ignore leading blanks-d, --dictionary-order

consider only blanks and alphanumeric characters-f, --ignore-case

fold lower case to upper case characters-g, --general-numeric-sort

compare according to general numerical value

-i, --ignore-nonprintingconsider only printable characters

-M, --month-sortcompare (unknown) < `JAN' < ... < `DEC'

-n, --numeric-sortcompare according to string numerical value

-r, --reversereverse the result of comparisons

Other options:
http://javarevisited.blogspot.com/2011/03/10-find-command-in-unix-examples-basic.htmlhttp://javarevisited.blogspot.com/2012/03/10-example-of-chmod-command-in-unix.html#ixzz1ybsKBzU0http://javarevisited.blogspot.com/2012/03/10-example-of-chmod-command-in-unix.html#ixzz1ybsKBzU0http://javarevisited.blogspot.com/2011/03/10-find-command-in-unix-examples-basic.htmlhttp://javarevisited.blogspot.com/2012/03/10-example-of-chmod-command-in-unix.html#ixzz1ybsKBzU0http://javarevisited.blogspot.com/2012/03/10-example-of-chmod-command-in-unix.html#ixzz1ybsKBzU0


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4, Lady Gaga, Title 118, Price $6.306, Elvis Presley, Title 335, Price $6.305, Johnny Cash, Title 482, Price $6.502, Taylor Swift, Title 723, Price $7.90

3, Mick Jagger, Title 610, Price $7.907, John Lennon, Title 271, Price $7.90

The -r option will reverse the sorting. For example,

$ sort -k7 -r test.txt

Yields

7, John Lennon, Title 271, Price $7.903, Mick Jagger, Title 610, Price $7.902, Taylor Swift, Title 723, Price $7.905, Johnny Cash, Title 482, Price $6.506, Elvis Presley, Title 335, Price $6.304, Lady Gaga, Title 118, Price $6.301, Justin Timberlake, Title 545, Price $6.308, Michael Jackson, Title 373, Price $5.50

In order to save the sorted list in a file you could use the"redirect" operator:

sort -k7 -r test.txt > test_new.txt

where "test_new.txt" would be the new file. Of course

you can also apply the sort command to the output of a

stream, such as the "pipe" operator:

$ ls -al | sort -r -n -k5

This sorts the output of the file listing generated by ls by

file size, starting with largest files. The -n operator

specifies "numeric" sorting as compared to alphabetic.
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With + option it's possible to give a sorting key

man sort

Code:

`+POS1[-POS2]'The obsolete, traditional option for

specifying a sort field.The field consists of the line between

POS1 and up to but _notincluding_ POS2 (or the end of the line

if POS2 is omitted).Fields and character positions are

numbered starting with 0.

[...]

To sort the file below on the third field

(area code):

Jim Alchin 212121 SeattleBill Gates 404404 SeattleSteve Jobs 246810 NevadaScott Neally 212277 Los Angeles

$ sort -k 3,3 people.txt> sorted.txt

or using the 'old' syntax:$ sort +2 -3 people.txt> sorted2.txt

Have you tried the example?

Here more examples...

------------------------------------------------


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$ cat example.txt

Jon 200

Bill 30

Carl 100Bernard 5

$ sort -k 2 -n example.txt

Bernard 5

Bill 30

Carl 100

Jon 200------------------------------------------------

$ ls -l | sort -n -r -k 5

-rw-r--r-- 1 root root 1057 1 mar 20:12 ring+star

-rw-r--r-- 1 root root 727 1 mar 20:12 A_star

-rw-r--r-- 1 root root 535 1 mar 20:12 star2

-rw-r--r-- 1 root root 505 1 mar 20:12 spirals_and_stars

-rw-r--r-- 1 root root 503 1 mar 20:12 curves-rw-r--r-- 1 root root 475 1 mar 20:12 simily

-rw-r--r-- 1 root root 458 1 mar 20:12 ring

-rw-r--r-- 1 root root 415 1 mar 20:12 stars

-rw-r--r-- 1 root root 387 1 mar 20:12 sprial

-rw-r--r-- 1 root root 377 1 mar 20:12 polys

Task: Append Data To A Text File

To append (add data to existing) data to a file called foo.txt, enter:

cat >>foo.txt


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Task: Number All Output Lines

Type the following command:

cat -n filenamecat --number filename

Task: View Non-printing Characters

To display TAB characters as ^I, enter:

cat -T filename

To display $ at end of each line, enter:

cat -E filenamecat --show-ends filename

Use ^ and M- notation, except for LFD and TAB and show allnonprinting:

cat -v filenamecat --show-nonprinting filename

To show all, enter:

cat -A fileName

OR


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cat -vET fileName

Sample outputs:

Fig.02: Unix / Linux cat command: View Non-printing Characters

Viewing All Files

You can simply use the shell wildcard as follows:

cat *

To view only (c files) *.c files, enter:
http://bash.cyberciti.biz/guide/Wildcardshttp://www.cyberciti.biz/faq/linux-unix-appleosx-bsd-cat-command-examples/cat-nonprinting-characters/http://bash.cyberciti.biz/guide/Wildcards


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cat *.c

Syntax:

The syntax is as follows:

cat file1cat > file2cat file3 | commandcat file4 | grep something

Examples:

cat file1cat file1 file2 > allcat file1 >> file2

What is wc ?

wc prints the number of lines, words and bytes in the given input. wc isthe abbreviation of word count.

3 wc Examples

Print the number of lines, words and characters in a file

To view the number of lines, words and characters in a file, give thefilename as argument to the wc command as shown below.

Syntax:

$ wc filenameX Y Z filename


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X Number of lines Y Number of words Z Number of bytes filename name of the file

$ wc demofile.txt36 104 570 demofile.txt

The above output indicates that the demofile.txt has 36 lines, 104words, and 570 bytes.

Print specific counts as required

You can use -l option to print only the line count as shown below.

$ wc -l demofile.txt36 demofile.txt

The same way you can use the following options for specificrequirements such as,

-w : print only word count -c : print only the byte count

You can also use any combination of above options.

Print the length of longest line

You can use -L option to print the length of longest line in the file.

$ wc -L demofile.txt84 demofile.txt

Syntax and Options

Short

Option

Long

OptionOption Description

-c bytes print the byte counts

-m chars print the character counts

-l lines print the newline counts


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If we want to skip some initial bytes of input files and then start thecomparison then -i option can be used

$ cmp -i 5 file1.txt file2.txt

file1.txt file2.txt differ: byte 18, line 1

So we see that the initial 5 bytes were skipped and hence cmpcomplains that byte 18 differs (which in example 1 was byte 23)

3. Skip different number of initial bytes from both input files

Another case could be when we would want to skip x bytes of inputin file1 and y bytes of input in file2. This could be achieved as

follows :

$ cmp -i 5:2 file1.txt file2.txtfile1.txt file2.txt differ: byte 2, line 1

So we see that we can give the option -i with x:y kind of input for thiscase. The output shows that this time the difference occurred very earlyat the second byte.

4. Display bytes that differ

If in the example 3 above we would also like to know the values ofindividual differing bytes being compared then the -l option can beused

$ cmp -l -i 5:2 file1.txt file2.txt2 156 115

3 141 1714 155 405 145 1566 40 1417 151 1558 163 14510 110 15111 151 163

12 155 4013 141 110


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default)

-l verboseOutput byte numbers andvalues of all differing bytes.

-n LIMIT bytes=LIMIT Compare at most LIMIT bytes.-s quiet silent

Output nothing; yield exitstatus only.

-v version Output version info.

help Output this help.

Comm.

NAMEcomm - select or reject lines common to two files

SYNOPSIScomm [-123] file1 file2

OPTIONSThe following options are supported:

-1 Suppresses the output column of lines unique tofile1.

-2 Suppresses the output column of lines unique tofile2.

-3 Suppresses the output column of lines duplicated in

file1 and file2.

NAME

diff - find differences between two files

SYNOPSIS

diff[options] from-file to-file


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DESCRIPTION

In the simplest case, diffcompares the contents of the two filesfrom-file and to-file. A file name of- stands for text read from the standard

input. As a special case, diff - - compares a copy of standard input toitself.

Iffrom-file is a directory and to-file is not, diffcompares the file infrom-file whose file name is that ofto-file, and vice versa. The non-directory file must not be -.

If bothfrom-file and to-file are directories, diffcompares corresponding

files in both directories, in alphabetical order; this comparison is notrecursive unless the -r or--recursive option is given. diffnevercompares the actual contents of a directory as if it were a file. The filethat is fully specified may not be standard input, because standard inputis nameless and the notion of ``file with the same name'' does notapply.

diffoptions begin with -, so normallyfrom-file and to-file may notbegin with -. However, -- as an argument by itself treats the remaining

arguments as file names even if they begin with -.

Options

Below is a summary of all of the options that GNU diffaccepts. Mostoptions have two equivalent names, one of which is a single letterpreceded by -, and the other of which is a long name preceded by --.Multiple single letter options (unless they take an argument) can be

combined into a single command line word: -ac is equivalent to -a -c.Long named options can be abbreviated to any unique prefix of theirname. Brackets ([ and ]) indicate that an option takes an optionalargument.-lines

Show lines (an integer) lines of context. This option does notspecify an output format by itself; it has no effect unless it iscombined with -c or-u. This option is obsolete. For proper

operation,patch typically needs at least two lines of context.-a


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Treat all files as text and compare them line-by-line, even if theydo not seem to be text.

-bIgnore changes in amount of white space.

-BIgnore changes that just insert or delete blank lines.

--briefReport only whether the files differ, not the details of thedifferences.

-cUse the context output format.

-C lines

--context[=lines]Use the context output format, showing lines (an integer) lines ofcontext, or three iflines is not given. For proper operation,patchtypically needs at least two lines of context.

--changed-group-format=formatUseformatto output a line group containing differing lines fromboth files in if-then-else format.

-dChange the algorithm to perhaps find a smaller set of changes.This makes diffslower (sometimes much slower).

-D nameMake merged if-then-else format output, conditional on thepreprocessor macro name.

-e

--edMake output that is a valid edscript.

--exclude=patternWhen comparing directories, ignore files and subdirectorieswhose basenames matchpattern.

--exclude-from=fileWhen comparing directories, ignore files and subdirectorieswhose basenames match any pattern contained infile.

--expand-tabs


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Expand tabs to spaces in the output, to preserve the alignment oftabs in the input files.

-fMake output that looks vaguely like an edscript but has changesin the order they appear in the file.

-F regexpIn context and unified format, for each hunk of differences, showsome of the last preceding line that matches regexp.

--forward-edMake output that looks vaguely like an ed script but has changesin the order they appear in the file.

-h

This option currently has no effect; it is present for Unixcompatibility.

-HUse heuristics to speed handling of large files that have numerousscattered small changes.

--horizon-lines=linesDo not discard the last lines lines of the common prefix and thefirst lines lines of the common suffix.

-iIgnore changes in case; consider upper- and lower-case lettersequivalent.

-I regexpIgnore changes that just insert or delete lines that match regexp.

--ifdef=nameMake merged if-then-else format output, conditional on thepreprocessor macro name.

--ignore-all-spaceIgnore white space when comparing lines.

--ignore-blank-linesIgnore changes that just insert or delete blank lines.

--ignore-caseIgnore changes in case; consider upper- and lower-case to be thesame.

--ignore-matching-lines=regexp

Ignore changes that just insert or delete lines that match regexp.


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--ignore-space-changeIgnore changes in amount of white space.

--initial-tabOutput a tab rather than a space before the text of a line in normalor context format. This causes the alignment of tabs in the line tolook normal.

-lPass the output throughprto paginate it.

-L label

--label=labelUse labelinstead of the file name in the context format and

unified format headers.--left-column

Print only the left column of two common lines in side by sideformat.

--line-format=formatUseformatto output all input lines in in-then-else format.

--minimalChange the algorithm to perhaps find a smaller set of changes.

This makes diffslower (sometimes much slower).-n

Output RCS-format diffs; like -fexcept that each commandspecifies the number of lines affected.

-N

--new-fileIn directory comparison, if a file is found in only one directory,

treat it as present but empty in the other directory.--new-group-format=format

Useformatto output a group of lines taken from just the secondfile in if-then-else format.

--new-line-format=formatUseformatto output a line taken from just the second file in if-then-else format.

--old-group-format=format


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Useformatto output a group of lines taken from just the first filein if-then-else format.

--old-line-format=formatUseformatto output a line taken from just the first file in if-then-else format.

-pShow which C function each change is in.

-PWhen comparing directories, if a file appears only in the seconddirectory of the two, treat it as present but empty in the other.

--paginatePass the output throughprto paginate it.

-qReport only whether the files differ, not the details of thedifferences.

-rWhen comparing directories, recursively compare anysubdirectories found.

--rcsOutput RCS-format diffs; like -fexcept that each command

specifies the number of lines affected.--recursive

When comparing directories, recursively compare anysubdirectories found.

--report-identical-files

-sReport when two files are the same.

-SfileWhen comparing directories, start with the filefile. This is usedfor resuming an aborted comparison.

--from-file=fileComparefile to all operands.file can be a directory.

--to-file=fileCompare all operands tofile. file can be a directory.

--sdiff-merge-assist


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Print extra information to helpsdiff.sdiffuses this option when itruns diff. This option is not intended for users to use directly.

--show-c-functionShow which C function each change is in.

--show-function-line=regexpIn context and unified format, for each hunk of differences, showsome of the last preceding line that matches regexp.

--side-by-sideUse the side by side output format.

--speed-large-filesUse heuristics to speed handling of large files that have numerousscattered small changes.

--starting-file=fileWhen comparing directories, start with the filefile. This is usedfor resuming an aborted comparison.

--suppress-common-linesDo not print common lines in side by side format.

-tExpand tabs to spaces in the output, to preserve the alignment oftabs in the input files.

-TOutput a tab rather than a space before the text of a line in normalor context format. This causes the alignment of tabs in the line tolook normal.

--textTreat all files as text and compare them line-by-line, even if theydo not appear to be text.

-u

Use the unified output format.--unchanged-group-format=format

Useformatto output a group of common lines taken from bothfiles in if-then-else format.

--unchanged-line-format=formatUseformatto output a line common to both files in if-then-elseformat.

--unidirectional-new-file


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When comparing directories, if a file appears only in the seconddirectory of the two, treat it as present but empty in the other.

-U lines

--unified[=lines]Use the unified output format, showing lines (an integer) lines ofcontext, or three iflines is not given. For proper operation,patchtypically needs at least two lines of context.

-v

--versionOutput the version number ofdiff.

-wIgnore white space when comparing lines.

-W columns

--width=columnsUse an output width ofcolumns in side by side format.

-xpatternWhen comparing directories, ignore files and subdirectories

whose basenames matchpattern.-Xfile

When comparing directories, ignore files and subdirectorieswhose basenames match any pattern contained infile.

-yUse the side by side output format.

Environmental Commands

logout orexit end terminal session

passwd change password

date print date & time

whoami orwho am i

list current user in that window

who list all users logged onto the workstation


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man

command1print on-line UNIX manual page forcommand1

ftp hostname

start file transfer protocol to transfer file between localand remote workstations. Remote workstation is namedhostname

telnet

hostnamelog onto remote workstation named hostname

df -k print list of disks and current capacity (in kilobytes)

setenv list environmental variables

which

commandlist location of executable command

File Manipulation

ls

list contents of current directory. Examples:lsfile.1 lists presence offile.1ls -l lists presence offile.1 with expandedinformationls -a lists contents of current directory, including filesthat start with "."

jotfile.1 opensjot editor; readsfile.1 intojot for editing

catfile.1 show contents offile.1 on screen

morefile.1show contents offile.1 on screen, but doesn't scrollpast top of screen

headfile.1 show first 20 lines offile.1 on screen

tailfile.1 show last 20 lines offile.1 on screen

difffile.1 file.2 shows differences betweenfile.1 andfile.2

wc

counts lines, words, and characters in filefile.1.Variations:wc -l counts lines in filefile.1wc -w counts words in filefile.1wc -m counts characters in filefile.1

cpfile.1 file.2copiesfile.1 tofile.2. Iffile.2 exists, it is overwritten.Originalfile.1 is not removed

mvfile.1 file.2movesfile.1 tofile.2. Iffile.2 exists, it is overwritten.

Originalfile.1 is removedrmfile.1 removefile.1. No utilities exist to retrieve it


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grep PATTERN

file.1print all lines that contain PATTERN infile.1

lprfile.1 printfile.1 on default laser printer

lpr Show list of available printers and questions to directyour printing of a file to a particular printer

du -sk

print size (in kilobytes) of current directory (".").Variations:du -sk * prints sizes (in kilobytes) of all files andsub-directoriesdu -skfile.1 prints size (in kilobytes) offile.1

compressfile.1

reduce the size offile.1 and replace it with a file

namedfile.1.Z. This compressed file is NOT a(readable) ASCII file.

uncompress

file.1.Zrestore the compressed filefile.1.Z

find . -name

file.1 -print

find the loation offile.1 in the directory and sub-directories. Variations:find . -name "*pattern" -print finds all files thatend withpattern.

find . -namefile.1 -exec rm '{}' ';' removes all filesnamedfile.1.

greppattern

file.1print only the lines offile.1 that containpattern

sortfile.1

displays contents offile.1 sorted alphabetically.Variations:sort -nfile.1 displays contents offile.1 sortednumerically

sort -rfile.1 displays contents offile.1 sortedalphabetically in reverse order.

Directory Manipulation

pwdshow the directory that you are in (present workingdirectory)

cd dir.1 change directory to dir.1

mkdir dir.1 make new directory dir.1


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rmdir dir.1 remove EMPTY directory dir.1

rm -r dir.1 remove directory dir.2 AND its contents

cp -r dir.1 dir.2 copy dir.1 (and its contents) to dir.2

mvfile.1 dir.1 movefile.1 to dir.1

ls

show contents of current directory. Variations:ls dir.1 shows contents ofdir.1ls -d dir.1 shows PRESENCE ofdir.1

du -skdir.1show sum of size (in kilobytes) ofdir.1 and itscontents

tar -cvfdir.1.tar

dir.1store an image ofdir.1 and it's contents in filefile.1

Process Control

command1& execute command1 in background

ps -ef print expanded list of all processes

killpid1 remove processpid1

interrupt current process

suspend current process

jobs display background and suspended processeskill %1 remove suspended process #1

top display the current, most computer-intensive commands

osview display the operating system statitistics

System Security

The following mechanism is the ONLY guaranteed method ofprotecting your work.

Each file and directory is owned by a user, and each user belongs to agroup. By default, users own their home directory (the current directorywhen the user logs in) and the contents of the home directory. Most

other files and directories are owned by "root" and other special users.


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The user assigns a type of privilege to each file and directory owned bythe user. By default, the privilege is rwxr-xr-x.

The first three characters ofrwxr-xr-x indicate that the owner can

read, write, and execute the file (or directory). The middle threecharacters indicate that all other users in the same group as the ownercan read and execute the file (or directory), but cannot write onto thefile (or directory), as indicated by the middle "-" character. The lastthree characters indicate that everyone else on the system can read andexecute the file (or directory), but cannot write onto the file (ordirectory), as indicated by the last "-" character.

To change the owner's permissions of a file (or directory), the ownercan type:

chown u+r file.1 chown u+w file.1 chown u+xfile.1

chown u-r file.1 chown u-w file.1 chown u-xfile.1

To change the group's permissions of a file (or directory), the ownercan type:chown g+r file.1 chown g+w file.1 chown g+xfile.1

chown g-r file.1 chown g-w file.1 chown g-xfile.1

To change the permissions of a file (or directory) for everyone else, theowner can type:chown o+r file.1 chown o+w file.1 chown o+xfile.1

chown o-r file.1 chown o-w file.1 chown o-xfile.1

SYNOPSIS


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touch [-acm] [-fagefile] [-ragefile] [[-t] time]file ...

touch [-acm] timefile ...

DESCRIPTION

The touch command changes certain dates for eachfile argument. By

default, touch sets both the date of last file modification and the date

of last file access to the current time. This is useful for maintainingcorrect release times for software and is particularly useful inconjunction with the MKS Make software development facility.

Options

-a

sets only the access time.

-c

does not create anyfiles that do not already exist. Normally,touch creates such files.

-m

sets only the modification time.

If you do not specify -a or-m, touch behaves as though you

specified both.

To tell touch to use a time other than the current, use one of the

following options:

-fagefile

is an obsolete version of the POSIX-compliant -r option.

-ragefile


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sets the access and modification times (as indicated by the otheroptions) to those kept foragefile.

-ttime

specifies a particular time using this format:

[[[[cc]yy]MM]dd]hhmm[.ss]

where cc is the optional first 2 digits of the year,yy is the optionallast 2 digits of the year,MMis the optional number of the month(01-12), ddis the optional day of the month, hh is the hour in 24hour format (required), mm is the minutes (required),ss is theoptional seconds.

An obsolete (but still supported) version of this command lets you omitthe -t, but the format is:

MMddhhmmyy[yy]

EXAMPLES

touch newfile

sets the modification time ofnewfile to the present.

touch -t 8001031305 oldfile

sets the modification time ofoldfile to 13:05 on January 3, 1980.

touch -r oldfile newfile

sets the modification time ofnewfile to that ofoldfile.

The unix touch command

Posted on September 11, 2008
http://charles.lescampeurs.org/2008/09/11/the-unix-touch-commandhttp://charles.lescampeurs.org/2008/09/11/the-unix-touch-command


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This post is a quick ref on the linux touch command. All the exampleshave been tested on Linux.

This command is used to update the access and modification times of

files.

touchs syntax

touch [option] file_name(s)touch file1 file2 file3

Here some examples:

# touch /tmp/file# ls -l /tmp/filerw-r--r-- 1 charlybr charlybr 0 Sep 10 16:13/tmp/file

Update access and modification time to currenttime:

# ls -l /tmp/filerw-r--r-- 1 charlybr charlybr 0 Sep 10 16:13/tmp/file# touch /tmp/file# ls -l /tmp/filerw-r--r-- 1 charlybr charlybr 0 Sep 10 16:14/tmp/file

Update access and modification time to a specified

timestamp ([[CC]YY]MMDDhhmm[.ss] format):

# touch -t 09091842 /tmp/file# ls -l /tmp/file-rw-r--r-- 1 charlybr charlybr 0 Sep 918:42 /tmp/file

Update access and modification time to a specified

date


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# touch -d '9 Sep' /tmp/file# ls -l /tmp/file-rw-r--r-- 1 charlybr charlybr 0 Sep 900:00 /tmp/file

# touch -d '9 Sep 2008 13:14' /tmp/file# ls -l /tmp/file-rw-r--r-- 1 charlybr charlybr 0 Sep 913:14 /tmp/file

Hack 25. Cut Command Examples

by Ramesh

Cut command can be used to display only specific columns from a textfile or other command outputs.

Following are some of the examples.

Display the 1st field (employee name) from a colon delimited file

$ cut -d: -f 1 names.txt

Emma ThomasAlex JasonMadison RandySanjay GuptaNisha Singh

Display 1st and 3rd field from a colon delimited file

$ cut -d: -f 1,3 names.txt

Emma Thomas:MarketingAlex Jason:SalesMadison Randy:Product DevelopmentSanjay Gupta:Support

Nisha Singh:Sales


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ood osgood os

If you omit the start and end positions, then the cut command prints theentire line.

cut -c- file.txt

3.Write a unix/linux cut command to print the fields using thedelimiter?

You can use the cut command just as awk command to extract the

fields in a file using a delimiter. The -d option in cut command can beused to specify the delimiter and -f option is used to specify the fieldposition.

cut -d' ' -f2 file.txtorunixlinux

This command prints the second field in each line by treating the spaceas delimiter. You can print more than one field by specifying theposition of the fields in a comma delimited list.

cut -d' ' -f2,3 file.txtor linuxunix goodlinux good

The above command prints the second and third field in each line.

Note: If the delimiter you specified is not exists in the line, then the cutcommand prints the entire line. To suppress these lines use the -soption in cut command.

4. Write a unix/linux cut command to display range of fields?

You can print a range of fields by specifying the start and end position.


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cut -d' ' -f1-3 file.txt

The above command prints the first, second and third fields. To printthe first three fields, you can ignore the start position and specify onlythe end position.

cut -d' ' -f-3 file.txt

To print the fields from second fields to last field, you can omit the lastfield position.

cut -d' ' -f2- file.txt

5. Write a unix/linux cut command to display the first field from/etc/passwd file?

The /etc/passwd is a delimited file and the delimiter is a colon (:). Thecut command to display the first field in /etc/passwd file is

cut -d':' -f1 /etc/passwd

6. The input file contains the below text

> cat filenames.txtlogfile.datsum.pladd_int.sh

Using the cut command extract the portion after the dot.

First reverse the text in each line and then apply the command on it.

rev filenames.txt | cut -d'.' -f1

Unix Shell commands

- 9:07 AM - 11 comments
http://www.scripterworld.com/search/label/Unix%20Shell%20commandshttp://www.scripterworld.com/2009/11/unix-cut-command-with-real-examples.html#comment-formhttp://www.scripterworld.com/search/label/Unix%20Shell%20commandshttp://www.scripterworld.com/2009/11/unix-cut-command-with-real-examples.html#comment-form


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Unix cut command with real examples

Uinx Cut command displays selected sections from each line of

a file.

Unix Cut command Syntax :

cut [OPTION]... [FILE]...

Linux Cut commnd options with examples

Unix cut command treats input data is made up of one range, or

many ranges separated by delimiter.

N character or field, counted from 1

N- from Nth byte, character or field, to end of line

N-M from Nth to Mth (included) byte, character or field

-M from first to Mth (included) byte, character or field

Let see the options of unix commands with examples.

My sample file contents

$ cat passwdfile

unixuser:x:501:506:Unix

User:/home/unixuser:/bin/bash

oradba:x:502:506:DBA

User:/home/oradba:/bin/bash
http://www.scripterworld.com/2009/11/unix-cut-command-with-real-examples.htmlhttp://www.scripterworld.com/2009/11/unix-cut-command-with-real-examples.html


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scripter:x:1658:506:Scripter

World:/home/scripter:/bin/bash

$

Unix cut c option

-c option specifies to output to display only these character

positions.

To display output of 10 character(N character) of each line

$ cut -c 10 passwdfile

x

5

x

$

To display output of 5 and 10 characters(N,M characters) ofeach line

$ cut -c 5,10 passwdfile

ux

b5

px

$

To display output from 5th to 10th characters(N-M characters) of

each line

$ cut -c 5-10 passwdfile

user:x


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ba:x:5

pter:x

$

To display output upto 10th character(-M charcters) of each line

$ cut -c -10 passwdfile

unixuser:x

oradba:x:5

scripter:x

$

To display output from 10th character(N- charcters) to end of the

each line

$ cut -c 10- passwdfile

x:501:506:Unix User:/home/unixuser:/bin/bash

502:506:DBA User:/home/oradba:/bin/bashx:1658:506:Scripter

World:/home/scripter:/bin/bash

$

Unix cut -d option and Unix cut -f option

-d The character following -d is the field delimiter . Default is tab.Space or other characters with special meaning to the shell must

be quoted. delim can be a multi-byte character.

-f specifies the fields to display from the list of fields formed from

the input data separate by delimter(-d) .Fields are counted from

one and separate multiple values by comma (,)

To get the user description(5th field) from our example file


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Scripter World:/home/scripter:/bin/bash

$

Unix cut last characterTo display a last character of a string

STRING="unixuser:x:501:506:Unix

User:/home/unixuser:/bin/bash"

echo ${STRING} awk '$0=$NF' FS=

$ STRING="unixuser:x:501:506:UnixUser:/home/unixuser:/bin/bash"

$ echo ${STRING} awk '$0=$NF' FS=h$

Use cut last field or columnTo display a last field of a string with a delimter (Here delimter is

":" colon)

STRING="unixuser:x:501:506:Unix


echo ${STRING} awk '$0=$NF' FS=":"

$ STRING="unixuser:x:501:506:Unix


$ echo ${STRING} awk '$0=$NF' FS=":"

/bin/bash

$


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First create the following demo_file that will be used in the examplesbelow to demonstrate grep command.

$ cat demo_file

THIS LINE IS THE 1ST UPPER CASE LINE IN THISFILE.this line is the 1st lower case line in thisfile.This Line Has All Its First Character Of TheWord With Upper Case.

Two lines above this line is empty.

And this is the last line.

1. Search for the given string in a single file

The basic usage of grep command is to search for a specific string inthe specified file as shown below.

Syntax:grep "literal_string" filename

$ grep "this" demo_filethis line is the 1st lower case line in thisfile.Two lines above this line is empty.

2. Checking for the given string in multiple files.

Syntax:grep "string" FILE_PATTERN

This is also a basic usage of grep command. For this example, let uscopy the demo_file to demo_file1. The grep output will also include thefile name in front of the line that matched the specific pattern as shownbelow. When the Linux shell sees the meta character, it does theexpansion and gives all the files as input to grep.

$ cp demo_file demo_file1


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$ grep "this" demo_*demo_file:this line is the 1st lower case linein this file.demo_file:Two lines above this line is empty.

demo_file:And this is the last line.demo_file1:this line is the 1st lower case linein this file.demo_file1:Two lines above this line is empty.demo_file1:And this is the last line.

3. Case insensitive search using grep -i

Syntax:grep -i "string" FILE

This is also a basic usage of the grep. This searches for the givenstring/pattern case insensitively. So it matches all the words such asthe, THE and The case insensitively as shown below.

$ grep -i "the" demo_file

THIS LINE IS THE 1ST UPPER CASE LINE IN THISFILE.this line is the 1st lower case line in thisfile.This Line Has All Its First Character Of TheWord With Upper Case.And this is the last line.

4. Match regular expression in files

Syntax:grep "REGEX" filename

This is a very powerful feature, if you can use use regular expressioneffectively. In the following example, it searches for all the pattern thatstarts with lines and ends with empty with anything in-between. i.e

To search lines[anything in-between]empty in the demo_file.


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The following example is the WORD grep where it is searching onlyfor the word is. Please note that this output does not contain the lineThis Line Has All Its First Character Of The Word With Upper Case,even though is is there in the This, as the following is looking onlyfor the word is and not for this.

$ grep -iw "is" demo_fileTHIS LINE IS THE 1ST UPPER CASE LINE IN THISFILE.this line is the 1st lower case line in thisfile.

Two lines above this line is empty.And this is the last line.

6. Displaying lines before/after/around the match using grep -A,

-B and -C

When doing a grep on a huge file, it may be useful to see some linesafter the match. You might feel handy if grep can show you not onlythe matching lines but also the lines after/before/around the match.

Please create the following demo_text file for this example.

$ cat demo_text4. Vim Word Navigation

You may want to do several navigation in

relation to the words, such as:

* e - go to the end of the current word.* E - go to the end of the current WORD.* b - go to the previous (before) word.* B - go to the previous (before) WORD.* w - go to the next word.* W - go to the next WORD.


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$ grep -B 2 "single WORD" demo_textExample to show the difference between WORD andword

* 192.168.1.1 - single WORD

6.3 Display N lines around match

-C is the option which prints the specified N lines before the match. Insome occasion you might want the match to be appeared with the linesfrom both the side. This options shows N lines in both the side(before& after) of match.

$ grep -C 2 "Example" demo_textword - word consists of a sequence of letters,digits and underscores.

Example to show the difference between WORD andword

* 192.168.1.1 - single WORD

7. Highlighting the search using GREP_OPTIONS

As grep prints out lines from the file by the pattern / string you hadgiven, if you wanted it to highlight which part matches the line, thenyou need to follow the following way.

When you do the following export you will get the highlighting of the

matched searches. In the following example, it will highlight all the thiswhen you set the GREP_OPTIONS environment variable as shownbelow.

$ export GREP_OPTIONS='--color=auto'GREP_COLOR='100;8'

$ grep this demo_filethis line is the 1st lower case line in thisfile.


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Two lines above this line is empty.And this is the last line.

8. Searching in all files recursively using grep -r

When you want to search in all the files under the current directory andits sub directory. -r option is the one which you need to use. Thefollowing example will look for the string ramesh in all the files inthe current directory and all its subdirectory.

$ grep -r "ramesh" *

9. Invert match using grep -v

You had different options to show the lines matched, to show the linesbefore match, and to show the lines after match, and to highlight match.So definitely Youd also want the option -v to do invert match.

When you want to display the lines which does not matches the givenstring/pattern, use the option -v as shown below. This example willdisplay all the lines that did not match the word go.

$ grep -v "go" demo_text4. Vim Word Navigation

You may want to do several navigation inrelation to the words, such as:

WORD - WORD consists of a sequence of non-blank

characters, separated with white space.word - word consists of a sequence of letters,digits and underscores.

Example to show the difference between WORD andword

* 192.168.1.1 - single WORD* 192.168.1.1 - seven words.


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10. display the lines which does not matches all the given pattern.

Syntax:grep -v -e "pattern" -e "pattern"

$ cat test-file.txtabcd

$ grep -v -e "a" -e "b" -e "c" test-file.txtd

11. Counting the number of matches using grep -c

When you want to count that how many lines matches the givenpattern/string, then use the option -c.

Syntax:grep -c "pattern" filename$ grep -c "go" demo_text

6

When you want do find out how many lines matches the pattern

$ grep -c this demo_file3

When you want do find out how many lines that does not match thepattern

$ grep -v -c this demo_file4

12. Display only the file names which matches the given pattern

using grep -l


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If you want the grep to show out only the file names which matched thegiven pattern, use the -l (lower-case L) option.

When you give multiple files to the grep as input, it displays the namesof file which contains the text that matches the pattern, will be veryhandy when you try to find some notes in your whole directorystructure.

$ grep -l this demo_*demo_filedemo_file1

13. Show only the matched string

By default grep will show the line which matches the givenpattern/string, but if you want the grep to show out only the matchedstring of the pattern then use the -o option.

It might not be that much useful when you give the string straightforward. But it becomes very useful when you give a regex pattern andtrying to see what it matches as

$ grep -o "is.*line" demo_fileis line is the 1st lower case lineis lineis is the last line

14. Show the position of match in the line

When you want grep to show the position where it matches the patternin the file, use the following options as

Syntax:grep -o -b "pattern" file$ cat temp-file.txt1234512345

$ grep -o -b "3" temp-file.txt


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2:38:3

Note: The output of the grep command above is not the position in theline, it is byte offset of the whole file.

15. Show line number while displaying the output using grep -n

To show the line number of file with the line matched. It does 1-basedline numbering for each file. Use -n option to utilize this feature.

$ grep -n "go" demo_text

5: * e - go to the end of the current word.6: * E - go to the end of the current WORD.7: * b - go to the previous (before) word.8: * B - go to the previous (before) WORD.9: * w - go to the next word.10: * W - go to the next WORD.

Additional Grep Tutorials

7 Linux Grep OR, Grep AND, Grep NOT OperatorExamples

Regular Expressions in Grep Command with 10Examples Part I

Advanced Regular Expressions in Grep Commandwith 10 Examples Part II

Search in a *.bz2 file using bzgrep, and *.gz file

using zgrep

Awesome Linux Articles

Following are few awesome 15 examples articles that you might findhelpful.

Linux Crontab: 15 Awesome Cron Job Examples Mommy, I found it! 15 Practical Linux Find

Command Examples 15 Examples To Master Linux Command Line History
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Unix LS Command: 15 Practical Examples

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1Joao Trindade March 28, 2009 at 3:54 am

You have a small glitch:>> 4. Match regular expression in files using grep -i

Dont you mean:4. Match regular expression in files using grep -e

The rest of the post is great.

2 Ramesh March 29, 2009 at 12:16 am

Joao,

Thanks for pointing it out. I have corrected it. Also, we can doREGEX without the option -e as shown in the example #4.

From Man Pages:

SYNOPSIS

grep [options] PATTERN [FILE...]grep [options] [-e PATTERN | -f FILE][FILE...]

-e PATTERN, --regexp=PATTERNUse PATTERN as the pattern; useful toprotect patterns beginning with -.

3 dragon March 31, 2009 at 11:26 pm

Hi:

FYI, tip 14 will be2:38:3on Ubuntu system. (including the \n character I guess

4 Ramesh March 31, 2009 at 11:44 pm

Dragon,
http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-7577http://thisblog.runsfreesoftware.com/http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-7605http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-7708http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-7711http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-7577http://thisblog.runsfreesoftware.com/http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-7605http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-7708http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-7711


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Thanks for pointing it out. Ive corrected it.

5Francesco Talamona April 26, 2009 at 2:48 am

I find very useful the following command, when you have to dealwith a very lengthy configuration file full of comments:

grep -v -E ^\#|^$ /etc/squid/squid.conf

It skips every line beginning with an hash (#) or empty, so youcan see at a glance the 15 lines edited out of a +4400 lines textfile.

BTW interesting topics, great posts

6 albar May 7, 2009 at 7:51 pm

help mehow to bzgrep : ^C02but ^C is count as one special character,in this word:

data1^C02data2

thanks

7 Ramesh Natarajan May 8, 2009 at 5:51 pm

@Francesco Talamona,

Thanks a lot for sharing your grep command example. Yes. allthose empty lines and comment lines can get very annoying when

you do grep. So, it is an excellent idea to hide them in the grepoutput with your examples.

8 sasikala May 11, 2009 at 9:41 pm

@albar,

try like this

grep \^C02
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9 albar May 12, 2009 at 1:18 am

@sasikala ,i do have try that too, but still got nothing,

but it works when and C count as two character

thanks

10 SathiyaMoorthy May 12, 2009 at 4:33 am

@albar

You should type ^C as ctrl-v + ctrl-c in grep as single character as$ grep ^C02 file

Dont escape, dont type it as ^ C as two characters. Hope thishelps.

11 albar May 12, 2009 at 8:59 pm

@sathiya,

god bless u allit works thanks

12 Manish Patel May 21, 2009 at 7:00 pm

Hi

I am trying to exclude the last word of all the line like sync.php,uploads.php, backup.php

File text include as below

/usr/home/htdocs/drag-and-drop/htdocs.php/usr/home//htdocs/sms/publish/pages/sync.php/usr/home/htdocs/track/backup.php/usr/home/htdocs/smstest/smstest.php/usr/home/htdocs/uploads.php

/usr/home/htdocs/017/backup.php
http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10095http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10109http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10159http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10582http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10095http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10109http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10159http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10582


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How can I achieve that using grep or sed or awk

Also how I can use * wildcard in sed command like to replace*.php to *.txt or any other extension.

Thank you in advance.

Manish

13 Francesco Talamona May 21, 2009 at 10:36 pm

Are you restricted to sed or awk?

1)dirname /usr/home/htdocs/drag-and-drop/htdocs.php/usr/home/htdocs/drag-and-drop

2)rename does what you want

14 Manish Patel May 24, 2009 at 6:55 pm

Hi,

Those lines are the contents of the text file and I dont want tochange the actual directory or the file on server. I want to changethe contents of the file where all file file names ending at the lineshould be removed. So the final file contents should look like this

cat filecontenet.txt

/usr/home/htdocs/drag-and-drop//usr/home//htdocs/sms/publish/pages//usr/home/htdocs/track//usr/home/htdocs/smstest//usr/home/htdocs//usr/home/htdocs/

I think rename would not help here in editing file contents.
http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10586http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10707http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10586http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-10707


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Thank youManish

15SathiyaMoorthy May 24, 2009 at 11:43 pm

rev filecontenet.txt | cut -d/ -f2- | rev

rev filecontenet.txt > reverses the file and pipes to cut command.cut -d/ -f2- > cuts off the first field ( cuts off last field, as it isreversed ).rev > prints the output given order.

16 P0B0T May 26, 2009 at 11:36 pm

Manish,

I believe youre looking for the following

sed -e s/.php$// filecontenet.txt

17 P0B0T May 26, 2009 at 11:39 pm

Sorry, didnt read your requirement carefully.

Try this:

sed -e s/\/[^/]*.php$/\// filecontenet.txt

18 Manish Patel June 5, 2009 at 5:31 pm

Hi

Thank you to Sathiya Moorthy and P0B0T.

Both solution worked very nicely for me.

P0B0T can you explain how your command works for eachdefined option s/\/[^/]*.php$/\//

Thank youManish
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19 mano June 10, 2009 at 3:00 am

The above info on grep is really great. I want to search for astring in all the files in the directory and add a $ symbol at the

start of the searched line and save in the same file.

20SathiyaMoorthy June 18, 2009 at 10:49 pm

@manoMore than using grep for this requirement, you can use sed whichis:sed -i s/.*abc.*/$&/ *

-i : edit the input file.s/// : substitute the matched pattern with the replacement string./.*abc.*/ : match the string abc/$&/ : Replace with $ followed by matched string.* : all the files in the current directory.

This is one way of satisfying your requirement, there may beother efficient ways.

Hope this helps.

21 mano June 19, 2009 at 12:17 am

Hi SathiaMoorthy, Thank u so much. it works fine. If I need tosearch for files in all subdirectories, how should this sedcommand modified?

Thanks in advance.

mano

22SathiyaMoorthy June 27, 2009 at 12:05 am

@manoModification in sed command is not needed.
http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-11335http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-11658http://www.thegeekstuff.com/http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-11660http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-11995http://www.thegeekstuff.com/tag/vi-vim-tips-and-tricks/http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-11335http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-11658http://www.thegeekstuff.com/http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-11660http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-11995http://www.thegeekstuff.com/tag/vi-vim-tips-and-tricks/


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To search for all files in the subdirectory.find . -type f

Execute the command on all those files with -exec.

find . -type f -exec sed -i s/.*abc.*/#&/ {} \;

But think twice before executing this command, because it willrecursively edit all the files. Taking backup before executing thiscommand is wise.

Refer the earlier article linux find command examples.

23 Vidya July 1, 2009 at 2:59 am

Hi,

I want to grep next 3 words in a line from the matching criteriaword..like if the line is

This is -g gateway -e enterprise -s server

Then I want to grep -g gateway -e enterprise from the line

Can you please help me in this case.Here gateway and enterprise value can be anything so need togrep next 3 words starting form -g

24 SathiyaMoorthy July 1, 2009 at 5:58 am

@Vidhya

$ grep -o -E -g \w+ -e \w+ FILENAME-g gateway -e enterprise

Explanation of the above command.,

-o : only matching ( point 13. )-E : extended regexp
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$ grep "not.*summer" file1line2: This is not summer.

$ grep "not" file1 | grep "summer"

line2: This is not summer.29 learner October 7, 2009 at 10:56 pm

@SathiyaMoorthy

Thank You for your very quick reply.

My question was not piping and hard coding every string , as i

mentioned multiple strings, i was looking for something in likesofgrep -F string1string2string3string4..stringn filename

which returns single occurrence of something like either string1,string2,.. stringn or all .., what i wanted was only string1 andstring2 and . stringn begin returned.[please note that i will be provided with strings as newlineseparated strings ,which i don't want to parse again and i haveconstraint of using grep only]

Thank You.

30 Ashish December 1, 2009 at 4:07 pm

Hi,

I need to sthing like thisI have a file containing 400 domainId values seprated by new lineex. domain.txtdomain1

domain2domain3
http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-18914http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-24442http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-18914http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-24442


79/101

I have a script that takes each domain and calls an api that returnsme an xml.like this for each domainval1domain1val2val3val4XXXval1

now i want to spit out the domain name in a file that does not

matches domainid value XXX.

how can i do it using grepTIA

31 Ashish December 1, 2009 at 4:16 pm

Hi,

I need to sthing like thisI have a file containing 400 domainId values seprated by new lineex. domain.txtdomain1domain2domain3

I have a script that takes each domain and calls an api that returns

me an xml.like this for each domain

val1domain1val2val3val4

XXXval1
http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-24445http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-24445


80/101

now i want to spit out the domain name in a file that does notmatches domainid value XXX.

how can i do it using grep

TIA

32 Varun December 17, 2009 at 7:16 am

Hi,The options mentioned in point 6 for displaying the context withA, B, & C does not seem to work on Solaris 10 with both grep &egrep

Is there a version of this grep available for Solaris?

Thank you,Varun.

33 Jawn Hewz December 21, 2009 at 7:54 pm

Does the -b (byte offset) work when greping binary files? I do not

get an offset returned when I grep a binary file, but I do whenusing a text file. I am using grep under Cygwin.

34fety January 11, 2010 at 3:32 am

thanks very much for this tutorial. it is very helpful..

35eMancu January 24, 2010 at 12:49 pm

Awsome tutorial!Im reading all your blog, its amazing!

36 Raghu Baba January 30, 2010 at 4:44 am

Hai.. I want to Parse my file .. Word to Excel .. so tell me somegrep & cut commands

37 Jeff Floyd February 1, 2010 at 6:54 pm
http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-26475http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-26926http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-29069http://ingafety.wordpress.com/http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-30788http://www.elblogolico.com.ar/http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-31545http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-32026http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-26475http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/#comment-26926http://www.thegeekstuff.

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