lecture1 2 intro-unix

Command Line Basics

Section Overview

X WindowsConsoles and TerminalsUNIX CommandsUNIX Filesystemvi Editor

X Windows

Familiar GUI interfaceVirtual screensRemote applicationsX-Terminal Windows Multiple concurrent session Scroll bars Cut, Copy & Paste

X Managers & Environments

X Window Managers Very configurable A lot of variety GUI login mode

X Window Environment Fully integrated environment Window manager runs within the

environment

Why use the command line?

Always available GUI not installed/working Remote sessions

More efficientMore powerfulBetter understanding of what is happening

UNIX Terminals

Old Days Hardwired – serial connections Modems – remote connections

Network – telnetConsole Monitor/keyboard/mouse on system Boot/error messages display Headless servers

Virtual Consoles in Linux

Multiple sessions on one consoleSpecial Consoles Console 1 – default console Console 7 – X Windows

Toggling between consoles Text mode - <Alt><Fn> X Windows - <Ctrl><Alt><Fn> <Fn>: Function Key (n = 1 .. 7)

Basic Philosophy

10% of work solves 90% of problemsSmaller is betterPortabilitySolve at right level

Be Creative!!!

Command Anatomy 101

command [-switches] [arg1] [arg2]…

Command: Name of the programSwitches: Modify command’s behaviourArg#: Arguments passed to command

Getting Help

Online manual availableSearchable Command/File name Type/Section Keyword

Not always easy to understand

Man Page SectionsSolarisSolaris LinuxLinux ContentsContents

1 1 User commands

2 2 System calls

3 3 Library calls

4 5 File formats

5 7 Misc. files and documents

6 6 Games and demos

7 4 Devices/Network protocols

1m 8 Administration commands

9 9 Kernel specs/interfaces (?)

Using man

man command Look up command

man n intro Contents of section n

man –k string Search short descriptions (apropos)

man –K string Search all man pages for string

Account Related Commands

login Start session

passwd Change Password

logout / exit Close session

File/Directory Commands

Files cp – Copy mv –

Move/Rename rm – Remove cat – View all more – View page less – View page

Directories ls – List contents mv – Move/Rename cd – Change Dir pwd – Current Dir mkdir – Create rm/rmdir – Remove

Copies, moves, and renaming

cp file1 file2|dir1 Copy file1 to file2 or into directory dir1

cp –r[p] dir1 dir2 Copy directory dir1 to dir2

mv file1 file2|dir2 Moves file1 to file2 or into directory dir1

Renames file1 to file2 if both in same directory

Viewing files

cat file1 Display the contents of file1 to the

screen

more file1 Display the contents of file1 one

screen at a time

less file1 Same as more but more powerful

Removing files and directories

rm file1 file2 ... Removes list of files

rmdir dir1 Removes dir1 only (if it is empty)

rm -r dir1 Removes dir1 and all

subdirectories/files VERY Dangerous!!!

Other directory commands

ls [-la] [file/dir list] Lists files in a directory

mkdir dir1 Creates directory dir1

cd dir1 Makes dir1 the current directory

pwd Displays the current directory path

UNIX Filesystem Hierarchy

/ (root)

bin var dev libusrrootbootetchomesbin

scott bobalice

n321 public_html

mail

bin sbin local tmplib

man lib srcsharebin

So many bins…

/ (root)

bin usrsbin

bin sbin local

sbinbin

bin directories: User programssbin directories: System programs/bin & /sbin – Needed at boot time/usr/bin & /usr/sbin – available when system fully operating

Windows Files/Directories

UNIX/LinuxUNIX/Linux WindowsWindows

/usr %SystemRoot% (C:\Windows)

/bin & /usr/bin

%SystemRoot%\System32

/dev %SystemRoot%\System32\Drivers

/etc %SystemRoot%\System32\Config

/tmp C:\Temp

/var/spool %SystemRoot%\System32\Spool

Source: Principles of Network and System Administration by Mark Burgess

Relative & Absolute Paths

Absolute Path Given from “root” directory Example: /usr/local/bin

Relative Path ‘.’ – Current Directory ‘..’ – Parent Directory ‘~’ – Home Directory Example: ~/.. = /home

Filter Commands

cat – View allmore – View pageless – View pagehead – View firsttail – View lastwc – word count

sort – Sort by fielduniq – Remove dupcut – Get fieldspaste – Merge Filesgrep – Search texttr – Replace text

Heads or Tails

head -# file Displays the first # lines of file1

tail -# file Displays the last # lines of file1

wc [-cwl] file Counts number of characters, words,

or lines in file

Sorting

Lists the contents of a file based on ordersort file Sorts file alphabetically by line

sort -r file Sorts file in reverse order by line

sort –t: -n +2 file Sorts file based on the 3rd field (+2) in numeric order (-n) with fields separated by ‘:’ (-t:)

Extracting info

cut –f# [-d%] file Displays # fields separated by %in file

grep search-string file Displays all lines with search-string in file

Can create very sophisticated search conditions

Changing file contents

paste file1 file2 Merge contents of file1 and file2

line by line

tr c1 c2 < file Changes all occurrences of

character c1 to c2 in file

Misc. Commands

date Set system time/date View (formatted) system time/date

cal Displays calendar

echo Display strings & shell variables

Visual Editor (vi)

Very Powerful3 modes Command Insert ex

Can be frustrating to learn initiallyImportant to have cheat sheet handy

emacs versus vi

Georgy says…

Slashdot (Asked by markhb): vi or emacs? Georgy:I'm so glad you asked!! Both. vi for quick editing, emacs (NOT xemacs) for coding projects. :q!:q!:q!

Source: Slashdot.com, 8/20/2003

Why vi?!?!?!

Because it is always there!!!

©www.nicedog.com

Installing Applications

Source Code Typically requires a C compiler (gcc) GNU Configure – Builds Makefile Read README file first!!!

Precompiled Packages Solaris: pkgadd RedHat Linux: rpm

RedHat Package Manager

Command line: rpm Install/Upgrade/Remove software Distribution verification Powerful package/file queries

Network Installations yum up2date apt-get