Linux/Unix Tutorial and Reference

by Sandeep Desai (http://www.thedesai.net)

I have installed Fedora Red Hat Linux, so this document is Red Hat centric but 90% of the information should apply to other Linux distributions and around 70% to Unix. This document is meant to be a quick reference for Linux/Unix information.

Books

Running Linux by Matt Welsh 4th Ed (O’Reilly)

UNIX in a Nutshell by Robbins (O’Reilly)

Linux/Unix

Unlike Microsoft Windows, you can view every part of the Linux as it is open source and it is very modular. You can look at every part of Linux e.g. the scripts that are used for booting. You can endlessly tinker with it. Also Linux is very modular, so you can startup a barebones with no Window Manager or with everything..

The kernel is the core part of Linux, which provides basic services such as running a program, accessing the hard disk, managing the hardware. The X-Windows is a layer which provides basic graphics services. The Window manager provides services such as moving, resizing the windows etc e.g. fvmw and kwin from KDE. The Desktop environment like KDE or GNOME provide a set of grapical applications to work with Linux.

X-Window consists of a server and a client, which can be both run on different machines. The first xclock is displayed on foohost1 and the second on foohost2. Note that you need to have an X-Windows server running on foohost1 and foohost2

rlogin –l foohost1

xclock &

setenv DISPLAY foohost2 :0.0

xclock&

LAMP (Linux Apache MySQL PHP)

LAMP is a very popular web development system.

Downloading software

Typical steps are

$./configure

$make

$make install

Security

• Do not use simple passwords
• Don’t share passwords
• Don’t run as root
• Keep software upto date
• View system logs (see syslogd)

Intrusions

• Denial of Service, bring down a server
• Snooping, intercepting data e.g looking at
• Distributed Denial of Service, sending a large number of requests to a server and overlaoding the server
• Virus, Worms, Trojans

Networking

Linux supports TCP/IP protocol. Every machine has a unique 128 bit address (IP address) expressed typically as 4 numbers e.g 111.222.333.444. 111.222 is the network part, 333 is the subnet and 444 is the host identifier.

A DNS (Domain Name Server) provides a name to IP address lookup.

Network configuration

• IP address (default 127.0.0.1)
• name (default is localhost)
• subnet mask (255.255.255.0)
• Gateway (to which all IP from this host should be directed)
• DNS Server (to do hostname to IP address translation

 
Optionally you can use DHCP (Dynamic Host Configuration Protocol) to request an IP address
 
Networking protocols

Protocol	Port
http	80
ftp
telnet
ssh
rsh

 
 
NIS (aka Yellow Pages) allows you to centrally manage accounts like Windows Domain Server. NIS has servers, slaves (copy of server NIS database) and client
NFS (Network File Server) allows you to mount a remote directory locally, does not do encryption. 
cat >> /etc/fstab
foohost:/usr /foo/bar NFS defaults
Ctrl-D
foohost should export /usr by adding it to /etc/exports
 

Networking file locations ?? /etc/rc.d/rc.inet1

tcpd is a wrapper which can be used to deny or allow access to certain hosts e.g can be used as a wrapper for fingerd. xinetd implements a TCP/IP wrapper around inetd. The TCP/IP wrapper checks /etc/hosts.allow and /etc/hosts.deny files before allowing a conneciton.

iptables IP filtering, rules are saved in /etc/sysconfig/iptables

KDE Desktop and kwin Window Manager

kde packages, kdegraphics, kdeutils, kdenetwork, kdeadmin, koffice,

kde konquerer (web browser) can do man :ls info :ls gg :linux // search google for linux

export PATH=/opt/kde3/bin :$PATH

export LD_LIBRARY_PATH=/opt/kde3/lib

exec startkde

Kdevelop an IDE for C

Gnome Desktop

Has Nautilus File Manager

Desktop folder in ~/.gnome-desktop

gphoto

ximian email etc

FVWM

.fvwm2rc or .fvwm or /usr/lib/X11/fvwm2/system.fvwmrc

X-Windows

On startup runs commands in users home directory .xinitrc or /usr/X11R6/lib/X11/xinit/xinitrc

Ctrl Alt – and Ctl Alt + to change resolution

Windows toolkit

Motif (outdated)

Qt is a C++ GUI toolkit used by KDE

GTK C GUI toolkit orginally developed for GIMP

Web sites

Web site
www.andamooka.org	Free Books
www.debian.org	Debian Linux Distribution
www.gnu.org	Linux/Unix utilities
savannah.gnu.org	Gnu Open Source projects
www.kernel.org	Linux Kernel
www.linuxfocus.org	Free online Linux magazine
www.linuxjournal.com	Linux journal magzine
www.linuxmagazine.com	Linux Magazine
www.linuxtoday.com	Linux Today
www.lwn.net	Linux Weekly web news
www.newsforge.com
www.redhat.com	Red Hat Linux has two distributions, Red Hat Enterprise Linux and Fedora Linux for consumers
fedora.redhat.com	Red Hat Distribution with latest Linux stuff
www.sourceforget.net	Open Source Projects with documentation and code
www.tldp.org	The Linux Documentation Project
www.winehq.com	Windows Emulator (Run Windows applications)
www.winimage.com/bootpart.htm	Add Partitions to Windows Boot Loader (c:\boot.ini)
linux-ntfs.sourceforge.net	Read Windows NTFS from Linux
www.symantec.com	Symantec Partition Magic (Formely Powerquest)
www.freshmeat.net	database of packages/applications available
www.ibiblio.org
comp.os.linux.announce
www.linuxcommand.org	Linux tutorial for new users
linux.about.com/library/cmd/blcmdl.htm	Linux command Reference and other linux info

Installing Fedora Linux dual boot with Windows XP

Download 1/i386/iso/yarrow-i386*.iso CD images (don’t download the SRPMS). Use Roxio for Windows to create a CD from the .iso file.

Change your PC BIOS boot sequence to boot from the CD first.

lilo is Linux boot loader (/etc/lilo.conf)

grub is Linux boot loader (/etc/grub.conf)

Dual boot info

You can use Partition Magic to resize your partitions without formating your data

If you overwrite the Windows XP Boot Loader with Grub or Lilo and your machine won’t boot. You can fix this by booting with your Windows XP CD, running the recovery console and running the fixmbr program. Windows stores the list of OS to run form in c:\boot.ini. You should use Grub or Lilo instead of the Windows Boot Loader.

Regular expression

Useful for pattern matching

^foo ?[0-9]ab*\ ? will match fooz4abcd ?

^ is first character

$ is last character

* any sequence

[x-y] range

? match any one character

\ escape to match one of the regular expression characters like ?

Linux/Unix Commands

See http://www.oreillynet.com/linux/cmd/

Some of the commands listed here should be run as root and will be found in the /sbin directory

Command	Description/Examples
adduser	add a user // Run as root copies files from /etc/skel such as .shrc
apropos	find man pages which match apropos format // man pages with format word
ar	Build library archive gcc –o foo.c ar rs libfoo.a foo.o (see gcc)
automount	automount file system. There will be one automount process per automount ps aux | grep automount
bison	GNU version of yacc, Generates parsers based on input grammar
bunzip
bzip	Newer than gzip, compresses 10-20% more
calls	calls foo.c // show function-call tree
cat	list contents of file
chmod	File permissions chmod +rwx foo chmod 777 foo
chown	change file owner
chsh ypchsh	change shell
compress	Old Unix programs to compress files
crontab	schedule tasks crontab hour minute day month dayofweek command crontab 0 2 15 * sun rm /foo.txt crontab –e // edit all entries crontab –l // list all entries crontab –u foo –e // run as root to edit crontab entries for user foo
cvs	Concurrent Version system, works with full directory trees, user works on a local copy of a project and then submits all the changes. setenv CVSROOT=/project/foo // CVS repository cvs init // create repository cvs import /somedir foocompnay footage cvs mkdir foo cvs checkout $CVSROOT/modules vi $CVSROOT/modules cvs checkout foodir cvs commit foo.c // checkin all the changes cvs commit cvs update // refresh local copy from repository should be done before a commit cvs release // we are done cvs is used for most open source projects and can be used over the network set CVS-RSH=ssh // default is rsh cvs –d ext:user@foodomain.com:/path/to/repository checkout foodir // work on a cvs session cvs –d :pserver:users@foodomain.com:/path/to/repository login
date	date 0101010004 This would set the date to January 1 (0101), 1 a.m. (0100), 2004. Require superuser privilege date +"%H %M %S" date -d '2 day' // todays date + 2 days date -d '-2 day' // todays date - 2 days
dd	create or copy file dd if=/dev/zero of=/test count=32768
df	disk free df -h
dhclient	request a new IP address using DHCP (dhcpd daemon)
diff	difference between two files diff –c foo.old foo.new > foo.patch patch –verbose < foo.patch // will update foo.old with changes from foo.new diff –cr foo.old foo.new > foo.patch // r is recursive patch –p) < foo.patch
dos2unix	see unix2dos
dmesg	Show kernel log
du	Disk Usage du -h // human readable output du --max_depth=2 . du -x --block-size=1024K | sort -nr | head –15 // show 15 largest files see df for disk free
dumpe2fs	dumpe2fs /dev/hda3 // loads of info about file system
fdformat	format floppy disk (superformat on debian)
fdisk	Partition hard disk /sbin/fdisk (see parted) fdisk -l
flex	Lexical analyzer code generator, used for creating language interpreters or compliers Generates C Code (see lex, bison, yacc)
fsck e2fsck	file system check fsck –t ext2 /dev/hda2 /dev/hda is entire hard diks /dev/hda2 is 2^nd partition do an unmount before doing a fsck ext2fs has a superblock which has important information about the file system, if this is corrupted, user cannot mount the file system. The superblock is backed up at every 8192+1 block, to recover run e2fsck –f –b 8193
free	shows memory usage and memory free in kilobytes
g++	Gnu C++ compiler, has same options has gcc
gcc	Gnu C Compiler gcc –v // version front end to /usr/lib/gcc-lib/machine/version e.g. /usr/lib/gcc-lib/i386-redhat-linux/3.2.3 gcc –o hello hello.c // if –o not used then executable file name is a.out gcc -c hello.c // produce object file, do not link gcc –g hello.c // -g is debug gcc –I../include –L ../lib –o a.c –lfoo // use libfoo.a library by default look in /usr/lib gcc –shared –o libfoo.so // create a shared library gcc –pg foo.c foo // put profiling information foo gprof foo gman.out (see ar, ld, calls)
gdb	GNU Debugger for C and C++ $gcc –g foo.c –o foo $gdb foo > list // show code > break 19 // breakpoint at line 19 >break foo.c:19 // breakpoint in foo.c at line 19 >run arg1 arg2 // run program with arguments >next // step over >step // step into >until 27 // run until line 27 >print var1 // print contents for var1 variable >backtrace // dump stack >quit $foo Segmentation fault $gdb foo core // run in bash ulimit –c unlimited to create core files >quit $gdb foo 123 // attach to process with pid 123 > continue >print var1=3 // assignment >ptype var1 // details of var1’s type >x/s var1 // dump memory of var1 as string >info // where we are >info locals // local variables >nexti // debug assembly >stepi
gprof	C Program Profiler, show in which functions program is spending the most time, used for optimizing C Programs $gcc –pg foo.c foo // put profiling information $foo $gprof foo gman
grep	grep text in file e.g. grep abcd *.java
groups	Which groups currently logged in user belongs to
gs	Ghostscript, A postscript file viewer.
gunzip	gunzip –c foo.txt.gz // equivalent to cat
gzip	Compress files gzip foo.txt // create foo.txt.gz gzip-l foo.txt.gz gunzip foo.txt.gz // uncompress file user tar to store multiple files into one .tar file (see compress and bzip)
hostname	show or set hostname, set in /etc/rc.d/rc.sysinit
ifconfig	Configure Network Interface, set host IP address, subnet mask etc (see route) /sbin/ifconfig eth0 // show network configuration info
inetd	Daemon which listens on many ports and starts a network server process such as ftpd or telnetd on request (see xinetd) /etc/inetd.conf or /etc/xinetd.conf
info	GNU documentation, maybe more detailed and up to date then man info ls (see man)
init	Run at boot time init 2 // Run all runlevel process from 1 to 2
insmod	add kernel loadable module to next boot
ipcs	Details on Inter Process Communications such as shared memory, semaphores, messages –l option returns limits
ipfilter	IP Packet filtering for security
kill	kill process kill –TERM 1234 // kill process 1234, See ps to get process details or see /proc directory
killall	kill process by name killall –TERM smbd nmbd
laptop_mode	/proc/sys/vm/laptop_mode turn on laptop mode
last	when user last logged in reads from /var/log/wtmp
ldconfig	/sbin/lconfig clears shared library cache, run after updating a shared library
ld	Link object files with libraries to create executable (see gcc)
ldd	ldd foo // lists libraries used by application ldd /usr/bin/X11/xterm see /etc/ld.so.conf see ldconfig when updating libraries .so libraries are loaded from /usr /usr/lib /etc/ld.so.conf and LD_LIBRARY_PATH environment variable
less	less foo.txt // page wise listing of text file can do page up and page down (see more)
lex	See flex
locate	locate indexed files
lpr	lpr foo // spool file for printing, printed by lpd daemon
ls	List directories ls –l // list all files -rwxrw-r—1 sdesai admin 1234 May 1 12 :00 a.txt
lsmod	/sbin/lsmod, list kernel loadable modules see insmod to add module
lspci	/sbin/lspci show PCI devices
make	Setup rules to build programs OBJECTS=a.o b.o # run shell command to get host name HOST_NAME=$(shell uname –n) # make sure you use tabs #each shell command is run in a different shell, so use ; to do it in one shell target: cd obj;rm * all: $(OBJECTS) gcc –o foo a.o b.o # rules can be set to build all *.o from *.c so that each individual file is not specified # $< is the *.c file %.o: %.c gcc –c –o $@ $< (see automake and autoconf for generating make files)
man	documenation of commands (See info command) man ls appropos edit // find all man pages with edit in the command if man does not work set $MANPATH properly
mkfs	make filesystem mkfs –t msdod /dev/fd0 fdformat /dev/fd0 (superformat on debian)
mknod	mknod /dev/foo b 6 13 create a block device with major number 6 and minor number 13
mkswap	Setup swap on file or device dd if=/dev/zero of = /swapfile bs=1024 count=32768 mkswap –c /swapfile 32768 chmod 0600 /swapfile swapon /swapfile swapoff /swapfile
modprobe	load kernel module
more	page wise list of text file cat foo.txt | more (see less)
mount	mount –t ext2 /dev/hda2 /mnt mount –t vfat /dev/hda3 (Mount Winodws 95/98 VFAT and FAT32 Partition) -ro switch mounts read only mount –a mounts all files in /etc/fstab
netstat	TCP/IP ports open (Works on windows) netstat –p // which daemons are listening on which ports netstat -f inet -a | grep LISTEN netstat –rn // show routing table
newgrp	assume group id (should be logged in) newgrp 7 // assume group id 7
parted	Partition Editor (See fdisk) /sbin/parted
passwd	change passwd, password stored in /etc/passwd or /etc/shadow
patch	patch changes from a new file to an old file diff –c foo.old foo.new > foo.patch patch –verbose < foo.patch // will update foo.old with changes from foo.new patch –R < foo.path // undo patch changes
ps	process Status ps –ef ps ax // all process ps –C httpd // httpd* processes See /proc directory
pstree	show list of process as tree, this will show the parent child relationship of processes
rdev	Change root mapping and etc rdev / /dev/hda3
rpm	Linux package manager used by Red Hat for installing/deinstalling software packages like mysql etc run as root rpm –e foobar // remove package rpm –q foobar // query package status rpm –ivh foobar // install foobar rpm –Uvh foobar // upgrade rpm –qa // list packages rpm –qf /usr/bin/foo // which package file foo belongs to rpm –ql foo // list files installed by the foo package
sed	cf=`echo $1 | sed 's/hello/world/g'` replace hello with world
setterm	terminal settings setterm –foreground white –background black setterm –store // save settings
swapon	Add Swap space to Linux swapon –a is run at boot-time from /etc/rc.d/rc.sysinit to add all swap from /etc/fstab
rlogin
route	/sbin/route add [-net | host] destination [gw gateway] [metric metric] options /sbin/route add default gw 1.2.3.4 metric 1 metric is for multiple routes, first try routes with lower metric number typically set in /etc/rc.d/rc.inet2 while booting
rsh hostname –l username –n command	password and userid on client and server machine should be same. Also /etc/hosts.equiv should have have hostname for machine from which rsh is being run. e.g rsh sbdesai-sun –l sbdesai –n ls
shutdown	shutdown –r now
sort	sort -m foo1 foo2 // merge files sort foo // sort files see uniq to remove duplicate lines
startx	Start X Windows server, runs commands in users home directories .xinitrc or /usr/X11R6/lib/X11/xinit/xinitrc
strace	show system calls being made by program useful to check if a long running program is still running strace foo strace –p 123 // system calls being made by a running process
stty	terminal settings stty –a // terminal settings stty erase ^H // use backspace for deleting stty quit ^X
su	switch user, login as another user su – foo // login as foo and run shell files such as .shrc etc su – root
superformat	format floppy disk in Debian (see fdformat for Red Hat)
telnet
tail –f filename	show bottom of file and keep displaying as file is updated (Good for viewing log files)
tar	create file archive of multiple files tar cvf foo.tar /etc /usr // create tar file tar xvf foo.tar // extract file tar tvf foo.tar // list contents tar cvzf foo.tar.gz /etc // gzip compressed tar ls –l foo.lst tar –cv –T foo.lst –f foo.tar // read foo.lst to for list of files to tar // script to make a copy of a directory cd source tar cf - . | (cd ../dest; tar xvf -)
touch	touch foo update to current date/time stamp for file
umask	File permissions to use when creating new files
uname	Print System name e.g output on Solaris is ‘SunOS’ uname –a // which kernel version etc uname -s // which Operating System uname -n // host name
uncompress
unmount	unmount /dev/hda3 unmount /mnt // unmount device of mount directory
uniq	Remove duplicate lines sort foo | uniq
unix2dos	see dos2unix
useradd	/sbin/useradd to add user
userdel	userdel –r foo //remove user foo, run as root
vi	Visual editor (vi cheat sheet)
vim	enhanched vi editor vim –g // launch GUI
xargs	add args to each line in input e.g find . –print | xargs cat
xclock	starts X-Windows clock
xfontsel	View Fonts in an X-Window
xhost	Allows access to show X-Windows remotely xhost +
xinetd	see inetd (Networking daemon)
xload	Show X-Windows system load average for X Display
xlsfonts	list fonts (command line)
xrdb	X Resources Database xrdb –load $HOME/.Xpreferences
xterm	start X-Windows terminal
valgrind	KDE Valgrind is a memory debugger at valgrind.kde.org gcc –g foo.c –o foo valgrind foo // will show invalid memory access as program runs valgrind –leak-check=yes –show-reachable=yes foo
yacc	Parser Generator (see bison)
ypwhich	query NIS database
w	who is logged in (see /var/log/utmp)
wc	word count e.g. wc –l for lines
which	show path for executable by searching $PATH
who am i	current user logged in

User commands

diff, patch

C Programming tools

gcc, calls, ar, ld, ldd, gdb, flex, bison, strace, valgrind (KDE)

diff, patch

RCS (Revision Control System)

ci foo.c

co –l foo.c

co –l1.1 foo.c

CVS (Concurrent Version System)

Consists of a central repository, developer make a local copy like a sandbox and modifies files locally, All changes are submitted to the repository. If another user has made a change to the file then we need to refresh our view and then checkin the files.

Shell/Script programming tools

perl, awk, sed, find, xargs

Kernel

System administration

adduser, strace (useful to check if a long running program is still running)

Networking

rsh, rexec, ssh, sshd, ping, telnet, rlogin, named, routed (obtain routing information) dhclient (DHCP Client) tcpd (TCP/IP Wrapper)

X-Windows

xterm

Daemons

xinetd (inetd), syslogd, routed, named

Unix Files & directories

/etc/exports	List directories which can be shared using NFS cat >> /etc/fstab foohost:/usr /foo/bar NFS defaults Ctrl-D foohost should export /usr by adding it to /etc/exports
/etc/fstab	device mount-point type options e.g. /dev/hda3 / ext3
/etc/group	List of groups groupname:passwd:gid:members
/etc/host.conf	how to resolve hostname to IP address order hosts,bind # first try /etc/hosts then DNS Server
/etc/hosts	hostname to IP address mapping, if DNS is setup properly this file should be almost empty localhost 127.0.0.1 # default entry foohost 12.34.56.78 (see ifconfig)
/etc/hosts.allow	list of hosts for which the xinetd or the tcpd should allow connections from
/etc/hosts.deny	list of hosts for which the xinetd or the tcpd should deny connections from
/etc/hosts.equiv	List of machines from which to allow remote connections for rsh/rcp/rlogin etc
/etc/inetd.conf /etc/xinetd.conf	List of daemon to start on connection request e.g start ftp server on ftp request.
/etc/init.d	list of services to run
/etc/inittab	Details of process to run while booting Process startup order is determined by the runlevel
/etc/ld.so.conf	list of directories where to search for shared object libraries .so are searched in /usr /usr/lib etc/ld.so.conf LD_LIBRARY_PATH see ldd and ldconfig
/etc/modules.conf	list of kernel loadable modules, see lsmod, insmod, modprobe
/etc/networks	used by route/routed
/etc/passwd	List of OS userids username:passwd:uid:gid:gecos:homedir:shell uid is unique userid (root is 0) gid is group id gecos is info like name
/etc/resolv.conf	list of DNS Servers search foo.net foo.com # which to domain to search in
/etc/services	list of network services and the port number that they use
/etc/sysconfig/iptables	iptables rules for IP packet filtering (see iptables)
/etc/sysctl.conf	Kernel settings such as shared memory etc
/etc/syslog.conf	syslogd configuration settings, where various log messages are sent e.g kernel log messages. Make configuration changes kill –HUP `cat /var/run/syslog.pid` and restart syslogd daemon for changes to take effect
/etc/X11/XF86Config	keyboard, mouse, Video Card and monitor configuration information (see startx)
/etc/yp.conf	NIS lookup info
/proc	Process information
/sbin	kernel and root level applications
/usr/src/linux	Linux sources maybe in /usr/src/kernel-source-vesion-number
/usr/lib/X11/rgb.txt	Color to name mapping can be used in X-Windows apps e.g xclock –fg black –bg white // The black and white are defined in the rgb.txt file
/usr/lib/X11/fvwm2/system.fvwmrc
/var/log/utmp	binary file, who is currently logged in (see w, finger, who)
/var/log/wtmp	binary file, when user last logged in (see last)

Files in users home directory

.fvwm

FVWM Windows Manager configuration file

Unix File System types

ext2	Most common, 256 character filenames, 32TB max size. Superblock stores important information, if corrupted (will be reported as mount failure) run e2fsck –f –b 8193 to restore from backup at block 8192+1
ext3
ramfs	RAM
cramfs	compressed RAM
msdos	MSDOS FAT
swap	Virtual Memory used by Unix, can have 8 partitions or files of 2GB each for total of 16GB on x86 (See mkswap)
vfat	Windows 95/96 FAT32
ntfs	Windows NT/2000/XP NTFS
proc	virtual filesystem for process information
devfs	/dev
iso9600	CD-ROM (High Sierra)
udf	CD-RW and DVD
smbfs	Access Windows Server

Booting (in approximate order)

· init process is started which starts processes listed in /etc/inittab

· inetd is daemon which listens for requests and then starts process listed in /etc/inted.conf e.g ftpd is only started when an ftp request is made this way we do not have large number of daemons listening for requests

· kernel messages are written to /var/log/messages (dmesg shows messages)

· /etc/init.d/autofs will automount from /etc/fstab (see /etc/auto.master)

Shutdown

shutdown –r now

Devices

Devices are in /dev directory they are either block devices or character devices. A device has a major number and a minor number. The major number indicates type of device and minor number is a unique number for different devices of the same type. See mknod

ls –l /dev

brw------- 1 root root disk 3, 0 Apr 1, 2004 foodev

/dev/camera
/dev/fd*	floppy disk
/dev/hda	First Hard disk
/dev/hda1	First Hard disk Partition 1
/dev/tty*	terminals
/dev/cdrom	CD-ROM/DVD-ROM drive
/dev/mem	Memory
/dev/null	cat /dev/null > foo.log to clear a file
/dev/usb

Steps to update library

// ftp://ftp.ibiblio.org/pub/linux

cp foo.so.6.4 /lib

cp foo.a /usr/lib

cd /usr/lib

ln –sf foo.so.6.4 foo.so.6

rm foo.so.6.3

/sbin/ldconfig

Scripts

// find files changed in the last 24 hours

find / -mtime –1 \! –type d –print

Vi commands

Has two mode, edit and command mode, to type in text pres i, to go into command mode press Esc

To save Esc-:x

Esc:set nu	Show linenumbers
a	append
i	Insert text
1,$s/search_string/repalcement_string/g	Search and repalce globally from 1 to last line
<Control> B	Move backward one screen
<Control> f	Move Forward one screen
<Control> d	move half a screen down
<Control> u	move half a screen up
G	move to end of file
65G	move to 65^th line in the file
0	move to begining of line
/mysearch	forward search for string ‘mysearch’
?mysearch	backward search for string ‘mysearch’
n	Next occurence of mysearch in the search direction
N	next occurence of mysearch in the opposite direction
R	Replace
u	undo command
x	delete character

ex mode press Esc :

r foo.txt	read file into edit buffer
r !ls -l	contents of ls –l in edit buffer
[x,y]s/pattern/replace/options	s/foo/foo2/g search foo with foo2 globally 1,10s/foo/foo2/g

registers a-z

ayy save to register a

ap paste from register a

Shell

When a user logins, they are working in a shell as defined in /etc/passwd. The popular shells are

• sh (Bourne Shell)
• ksh (Korn Shell)
• csh (C Shell
• tcsh (enhanced C Shell)
• bash (Bourne again shell)

Globbing is where the shell replaces a pattern like *.pl with all the files that match

$cat *.pl # becomes cat a.pl b.pl c.pl

$ echo $SHELL

$cat > xyz

[1] 1234

$jobs

1 cat > xyz

$fg 1 // bring job 1 to foreground

Ctrl-Z suspend process

Ctrl-S suspend terminal

Ctrl-Q resume terminal

Ctrl-

tcsh and bash support command line editing

export VISUAL=vi

export VISUAL=emacs

noclobber=1

set noclobber // do not overwrite files

C Shell

cat .cshrc

alias foo cat foo

export path = ($PATH /usr/bin)

.login is executed first time user logs in

.cshrc is executed every time csh is run

Set var=value Set’s var environment variable

Source xyz.csh Runs script in current shell (so environment variables will be set in current shell)

Korn Shell (ksh)

.profile is launched first time ksh is run

.shrc script is run on every invocation of ksh

. xyz.ksh (Runs the script in the current shell instead of launching a shell and running in it)

if test $1 == $2

then echo “match”

else echo “nomatch”

fi

Bourne Again Shell (bash)

cat .bashrc
tarc () {tar cvf $1.tar $1 }
 
 
Linux Software 

apache	www.apache.org Apache Web Server
blender3d
eclipse	open source IDE www.eclipse.org
gimp	Gnu Image Manipulation (like Jasc Paintshop Pro)
gnome	www.gnome.org Windows Manager
imagemagick	www.x.org import foo.jpg // capture window to image import –root window foo.jpg // capture screen display foo.jpg convert foo.bmp foo.jpg //convert scale rotate etc mogrify // like convert but overwrites original file montage *.jpg // combine images identify –verbose foo.jpg // image file info
java	www.blackdown.org
kde	www.kde.org Windows Manager
mtools	read DOS partitions, To work with DOS floppies, fdformat, mformat, can do mdir, mcopy, mmd., most dos commands prefixed with an m
mozilla	www.mozilla.org Web Browser
mysql	www.mysql.org SQL Database
openoffice	www.openoffice .org (like Microsoft Office)
perl	www.perl.org popular cross platform scripting language, has modules for working with web servers, databases etc www.perl.com www.pm.org
php	www.php.net Scripting language for building web applications
povray	Ray tracing
python	www.python.org Python Programming Language
samba	www.samba.org Make Linux into Windows file server
Tcl/Tk	www.tcl.tk Scripting language and GUI construction toolkit
vim	www.vim.org Enhanced VI editor
xfree86	www.xfree86.org X-Windows,
xmms	www.xmms.org mp3 player

Solaris

prtconf	Print System Configuration prtconf | grep Mem
showrev –p	shows list of patches installed
truss	print list of system calls a process is making, useful for finding out if a process has hung e.g truss –p –v all 1234 (1234 is process id)

CDROM is accessible as /cdrom. To eject do cd /cdrom; eject

On Solaris, you can use the rdate command (As root) to set your system's time against a remote server:

rdate olapvob3.us.oracle.com

To get this to happen regularly, as root run crontab -e

crond is the daemon that runs commands periodically.  Add a line that looks like

0 * * * * rdate olapvob3.us.oracle.com > /dev/null 2>&1

if there isn't one already.  This will cause your system to set its time against olapvob3 every hour.

Apache

Installed in /usr/sbin/httpd or /etc/apache (on debian)

start by running /etc/init.d/httpd <start|stop|restart>

httpd –f /etc/httpd/httpd.conf

httpd -l

/etc/httpd directory contains configuration files

/var/log/httpd contains log file information

httpd.conf is the configuration file

httpd.conf

DocumentRoot	Directory from which HTML documents should be displayed
LoadModule	Apache dynamically loaded extension modules e.g Perl Module
ScriptAlias	/cgi-bin/ /foo/cgi-bin # location of CGI scripts
ServerRoot	where configuration files are (default /etc/httpd)
ServerType	run as inetd or daemon
Listen	Port to listen on, below 1024 requires root access default is 80
DirectoryIndex	file to show when only url entered (default should be index.html)
<Directory “/foo/bar”> order allow,deny </Directory>

access.conf

.htaccess located in each directory which lists permissions for file access

MySQL

/usr/bin or /usr/local/bin or /etc/init.d/mysql

mysql // start server

scripts/mysql_install_db

mysqladmin version

mysql –u root

Ø show databases

Ø set password for root=password(‘newpassword’);

Ø flush privileges

Ø create database foo

Ø use database foo

Ø show tables

PHP (Hypertext processor)

Scripting language like Microsoft ASP (Active Server Pages) and Java Server Pages that allows you to mix HTML and the PHP scripting language to develop web applications

<?php

phpinfo();

?>

Samba (Access Unix directories from Windows as a Windows share)

Samba supports Microsoft SMB (Server Message Block) aka Common Internet File System protocol.

Install samba from www.samba.org

download samba*.Z to samba directory

gunzip samba*.Z

tar xvf samba*.tar

cd source

./configure

make

make install

cd ../packaging/Solaris

mkpkg.sh

cd /tmp

su root

pkgadd –D . samba (Solaris)

su root

// older version

pkgadd –d . SAMBAroot (Solaris)

pkgadd –d. SAMBAusr (Solaris)

To restart samba (file maybe called samba.server or smb)

/etc/init.d/samba stop

/etc/init.d/samba start

/usr/local/samba/bin/smbd –D

/usr/local/samba/bin/nmbd –D

To stop run killall –TERM smbd nmbd

smbmount //foohost/c_drive /test –o fooname/foodomain // may have to run as root

smbmount //foohost/c_drive /test –o credentials=/etc/foo // foo contains userid passwd

smbclient allows you to browse a Windows share (like a ftp)

>ls

>quit

Use dos2unix, unix2dos to convert ascii files, windows user \r\n (Carraige return-Line Feed) to terminate line, Unix use \n

Messages logged to /var/log/samba

smbpasswd to manager user/passwd

smbpasswd –a username // so that we donot have to enter passwords for smbmount

shares are listed in /usr/local/samba/lib/smb.conf or /opt/samba/lib/smb.conf or /etc/samba/samba.conf file listed below is a sample smb.conf file

Run testparm to check that samba configuration file is OK

# applies to all

[global]

guest account = sbdesai

# share all users home directories

[homes]

# workgroup = NT-Domain-Name or Workgroup-Name, eg: REDHAT4

workgroup = WALT-DCNT

# server string is the equivalent of the NT Description field

server string =

# Security mode. Most people will want user level security. See

# security_level.txt for details.

security = share

# Use password server option only with security = server

; password server = WALT-DCNT-PDC

# Most people will find that this option gives better performance.

# See speed.txt and the manual pages for details

socket options = TCP_NODELAY

# Browser Control Options:

# set local master to no if you don't want Samba to become a master

# browser on your network. Otherwise the normal election rules apply

local master = no

# Use only if you have an NT server on your network that has been

# configured at install time to be a primary domain controller.

domain controller = WALT-DCNT-PDC

# DNS Proxy - tells Samba whether or not to try to resolve NetBIOS names

# via DNS nslookups. The built-in default for versions 1.9.17 is yes,

# this has been changed in version 1.9.18 to no.

dns proxy = no

#============================ Share Definitions ==============================

[ade]

comment =

path = /ade

public = yes

writable = yes

hosts allow = 138.1.196.199 138.1.196.200 138.1.196.240

[emdw]

comment =

path = /users/sbdesai/.ade/view_storage/sbdesai_emdw_main2/emdw

public = yes

writable = yes

hosts allow = 138.1.196.199 138.1.196.200 138.1.196.240