file management commands cat cat command cat cal.txt cat command displays the contents of a file...
DESCRIPTION
cat Cat command cat cal.txt cat command displays the contents of a file here cal.txt on screen (or standard out).TRANSCRIPT
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File Management commands
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catCat command
cat cal.txt cat command displays the contents of a file here cal.txt on screen (or standard out).
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Cat > filenameCat command
cat > cal.txt cat output the contents to a file here cal.txt. It is redirecting the contents to the file.
touch filename
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ls
ls command is most widely used command and it displays the contents of directory.
options ls will list all the files in your home directory, this command has
many options. ls -l will list all the file names, permissions, group, etc in long
format. ls -a will list all the files including hidden files that start with . . ls -lt will list all files names based on the time of creation, newer
files bring first. ls -Fxwill list files and directory names will be followed by slash. ls -Rwill lists all the files and files in the all the directories,
recursively. ls -R | more will list all the files and files in all the directories, one
page at a time.
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ls-rw-r--r-- 1 lnp5jb 777 Dec 18 lookup.icn
The first set of characters in the output from the command (-rw- r-- r--) gives the permissions. The username in the middle of the line (lnp5jb) is the owner of the file. This is user who created the file. The following fields tell you the number of characters in the file, the date it was created and the name of the file.
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mkdirmkdir mkdir deep will create new directory, i.e. here deep
directory is created.
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cdCd command.
cd sandeep will change directory from current directory
to sandeep directory. Use pwd to check your current directory and ls to see if sandeep directory is there or not. You can then use cd sandeep to change the directory to this new directory.
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headhead filename by default will display the first 10 lines of a
file.
If you want first 50 lines you can use head -50 filename or for 37 lines head -37 filename and so forth.
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tailTail command.
tail filename by default will display the last 10 lines of a file. If you want last 50 lines then you can use tail -50 filename.
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moreMore command. more command will display
a page at a time and then wait for input which is spacebar. For example if you have a file which is 500 lines and you want to read it all. So you can use
more filename
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wcWc command
wc command counts the characters, words or lines in a file depending upon the option.
wc filename
wc -l filename will print total number of lines in a file. wc -w filename will print total number of words in a
file. wc -c filename will print total number of characters in
a file.
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File command displays about the contents of a given file, whether it is a text (Ascii) or binary file. To use it type
file filename
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cpCp command.
cp command copies a file. If I want to copy a file named oldfile in a current directory to a file named newfile in a current directory.
cp oldfile newfilecp –p olddir nerdir
If I want to copy oldfile to other directory for example /tmp thencp oldfile /tmp/newfile.
options available with cp are -p and -r . -p options preserves the modification time and permissions, -r recursively copy a directory and its files, duplicating the
tree structure.
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mvmv command is used to move a file from one
directory to another directory or to rename a file.
Some examples: mv oldfile newfile will rename oldfile to newfile. mv -i oldfile newfile for confirmation prompt. mv -f oldfile newfile will force the rename even
if target file exists. mv * /usr/bajwa/ will move all the files in current
directory to /usr/bajwa directory.
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lnLn command.
Instead of copying you can also make links to existing files using ln command.
If you want to create a link to a file called coolfile in /usr/local/bin directory then you can enter this command. ln mycoolfile /usr/local/bin/coolfile
Some examples: ln -s fileone filetwo will create a symbolic link and can exist across machines.
ln -n option will not overwrite existing files. ln -f will force the link to occur.
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rmRm command.
To delete files use rm command. Options:
rm oldfile will delete file named oldfile. rm -f option will remove write-protected files
without prompting. rm -r option will delete the entire directory as
well as all the subdirectories, (use with care)
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rmdirRmdir command.
rmdir command will remove directory or directories if a directory is empty.
Options: rm -r directory_name will remove all files even
if directory is not empty. rmdir sandeep is how you use it to remove
sandeep directory. rmdir -p will remove directories and any parent
directories that are empty. rmdir -s will suppress standard error messages
caused by -p.
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Misc Commands
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Misc CommandsMan ual command.
man man This is help command, and will explains you about online manual pages you can also use man in conjunction with any command to learn more about that command for example.
man ls will explain about the ls command and how you can use it.
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bannerBanner command.
banner prints characters in a sort of ascii art poster.
banner aman will print aman on screen
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calCal command
cal command will print the calander on current month by default. If you want to print calander of august of 1965. That's eightht month of 1965. cal 8 1965 will print following results.
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clearClear command clear command clears the screen and puts
cursor at beginning of first line.
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echoecho commandThe echo command 'echoes' its argument to
the standard output. This means that in its simplest form it prints something out on screen. For example:
echo Hello - you type Hello - response from the shell
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wildcardsWildcardsWildcard characters can be used to identify directory
and file names. The wildcard character * is used to refer to any combination of characters. For example:
ls * - refers to all files cat test* - refers to all files starting with 'test', e.g.
'test', 'testing', 'test.c', etc. The wildcard character ? is used to refer to a single character. For example:
ls test? - refers to files starting with 'test' followed by a single character e.g. 'test1', 'test2', 'testz', etc.% cat test.? - refers to all files starting with 'test' with a single character after the full stop, e.g. 'test.c, test.f'
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chmodThe command chmod is used to change the
permissions on a file. The format of this command is:
chmod mode filename