Command Line Interface (CLI)

CSCI N321 – System and Network Administration

Copyright © 2000, 2011 by Scott Orr and the Trustees of Indiana University

Section Overview

X WindowsConsoles and TerminalsUNIX CommandsUNIX Filesystemvi Editor

References

CQU COIT13146 System Administration Course Chapter 4 Chapter 5

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 behavior Windows typically uses “/” instead of “-”

Arg#: Arguments passed to command

Getting Help

Online manual availableSearchable Command/File name Type/Section Keyword

Not always easy to understand

Man Page SectionsLinuxLinux ContentsContents

1 User commands

2 System calls

3 Library calls

5 File formats

7 Misc. files and documents

6 Games and demos

4 Devices/Network protocols

8 Administration commands

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|dir1 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

Windows (MSDOS) File/Directory Commands

Files copy – Copy move – Move rename - Rename del – Remove type – View all more – View page

Directories dir – List contents xcopy – Copy move – Move rename - Rename cd – Change Dir md/mkdir – Create rmdir – Remove

Linux 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

Windows Registry (regedit)

/tmp C:\Temp

/var/spool %SystemRoot%\System32\Spool

Source: Principles of Network and System Administration by Mark Burgess

Windows RegistryHierarchical database of all system settingsRegeditOrganization Hives – Top level Keys – Individual settings within a hive

HKEY_LOCAL_MACHINEHKEY_LOCAL_MACHINE

HKEY_CLASSES_ROOTHKEY_CLASSES_ROOT

HKEY_CURRENT_CONFIGHKEY_CURRENT_CONFIG

HKEY_CURRENT_USERHKEY_CURRENT_USER

HKEY_USERSHKEY_USERS

Relative & Absolute Paths

Absolute Path Given from “root” directory Example:

/usr/local/bin (Linux) c:\windows\system32 (Windows)

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

More or Less

cat file Displays entire file to screen MSDOS - type

more file Displays file one screen at a time Same in MSDOS

less – replacement for more

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

MSDOS - find

Extracting info

cut –f# [-d%] file Displays # fields separated by %in file awk is a more advanced replacement

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

Can create very sophisticated search conditions

MSDOS - find

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 Same in MSDOS

Visual Editor (vi)

Very Powerful3 modes Command Insert ex (very similar to MSDOS edlin)

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!!!

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