Unix Commands

From Null-pointer

Contents 1 Adding a user 2 Groups 2.1 Add a group 2.2 Add a new user to a group 2.3 Add a existing user to existing group 3 Set password to never expire 4 .profile 4.1 Advanced alias 5 Fixed IP Address 6 Getting the IP Address Using DHCP 7 Snoop 8 Untar 8.1 Untar multiple files 9 rpm 10 yum 10.1 finding out what package to download for a dependency 11 output redirect 12 find files 12.1 count files in a folder 12.2 Find files containing "string" 13 How much disk space is a folder taking 14 Set Date, Time, and Zone 14.1 ntp 15 services 16 http_proxy 17 DISPLAY 18 killall 18.1 kill all tomcats 19 error: cannot open Conflictname index using db3 20 Version 21 Navigating 22 References

Adding a user

As root user.

[root@localhost ~]# useradd -d /export/home/[username] [username]

[root@localhost ~]# chown [username] /export/home/[username]

[root@localhost ~]# passwd [username]

Groups

What group am I

[KaneP01@localhost root]# groups KaneP01

[root@localhost ~]# groups root bin daemon sys adm disk wheel

• taken from http://www.cyberciti.biz/faq/which-groups-do-i-belong-to/

Add a group

[root@localhost ~]# groupadd newGroup^[1]

Add a new user to a group

[root@localhost ~]# useradd -G group newUser^[1]

Add a existing user to existing group

[root@localhost ~]# usermod -a -G ftp KaneP01

• taken from http://www.cyberciti.biz/faq/howto-linux-add-user-to-group/

Set password to never expire

[root@localhost ~]# passwd -x -1 [username]

.profile

SHELL=/usr/bin/bash
PS1=$'\\[\\033[1;30m\\][\\[\\033[1;37m\\]\\\\u\\[\\033[0;37m\\]@\\[\\033[1;37m\\]\\\\h\\
[\\033[1;30m\\]:\\[\\033[1;36m\\]\\W\\[\\033[1;30m\\]]\\[\\033[0;37m\\] '
alias ls='ls -F'

• Bash history
• Unix prompts

Advanced alias

# Default to human readable figures
alias df='df -h'
alias du='du -h'

alias ls='ls -hF --color=tty'                 # classify files in colour
alias dir='ls --color=auto --format=vertical'
alias ll='ls -l'                              # long list

Fixed IP Address

# cd /etc/sysconfig/network-scripts
# less ifcfg-eth0

DEVICE=eth0
IPADDR=192.168.1.100
NETMASK=255.255.255.0

BOOTPROTO=static
ONBOOT=yes

#
# The following settings are optional
#

BROADCAST=192.168.1.255
NETWORK=192.168.1.0

Getting the IP Address Using DHCP

# cd /etc/sysconfig/network-scripts
# less ifcfg-eth0

DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes

Snoop

snoop -o network.snoop port 8080

Untar

[root@localhost ~]# tar xvzf file-1.0.tar.gz

[root@localhost ~]# tar xvjf file-1.0.tar.bz2

[root@localhost ~]# tar xvf file-1.0.tar

• x = eXtract, this indicated an extraction ( c = create to create )
• v = verbose (optional) the files with relative locations will be displayed.
• z = gzip-ped; j = bzip2-zipped
• f = from/to file ... (what is next after the f is the archive file)

• taken from http://how-to.wikia.com/wiki/How_to_untar_a_tar_file_or_gzip-bz2_tar_file

Untar multiple files

[root@localhost ~]# for i in *.tar.gz; do tar -xvzf $i; done ^[2]

rpm

• RPM

yum

• Downgrading packages

finding out what package to download for a dependency

[root@localhost ~]# yum provides 'libXm.so.3'

output redirect

[root@localhost ~]# ls > outfile.txt 2>&1

also works in 4NT

find files

[root@localhost ~]# find . -name "ruby" -print

[root@localhost ~]# find . -name "*ruby*" -print

taken from http://www.athabascau.ca/html/depts/compserv/webunit/HOWTO/find.htm

count files in a folder

[root@localhost ~]# ls | wc -l ^[3] 939

Find files containing "string"

[root@localhost ~]# find . -type f | xargs grep string ^[4]

How much disk space is a folder taking

[root@localhost ~]# du -hcs 19G . 19G total

Set Date, Time, and Zone

[root@localhost ~]# date -s "11 MAR 2010 16:25"

[root@localhost ~]# ln -sf /usr/share/zoneinfo/Europe/London /etc/localtime

[root@localhost ~]# vi /etc/sysconfig/clock ZONE='Europe/London' UTC=false ARC=false

• http://www.cyberciti.biz/faq/howto-set-date-time-from-linux-command-prompt/
• http://www.wikihow.com/Change-the-Timezone-in-Linux

ntp

if using ntp

[root@localhost ~]# /sbin/service ntpd stop

Immediately reset the clock to the correct time

[root@localhost ~]# ntpd -g -q

[root@localhost ~]# /sbin/service ntpd start

services

start

[root@localhost ~]# svc -u /service/myservice

stop

[root@localhost ~]# svc -d /service/myservice

uptime

[root@localhost ~]# svstat -d /service/myservice

http_proxy

[root@localhost ~]# export http_proxy='http://www.proxy.com:80'

DISPLAY

[root@localhost ~]# export DISPLAY=my_machine_name:0.0'

killall

kill all processes^[5]

kill all tomcats

[root@localhost ~]# killall java

beware that this will kill everything being run by java!.

error: cannot open Conflictname index using db3

With error:

error: cannot open Conflictname index using db3 - No such file or directory (2)
error: can't create transaction lock on /var/lib/rpm/__db.000

Solve:

# rm -rf /var/lib/rpm/__db.*
# rpm --rebuilddb

Version

[root@localhost ~]# [cognos@gl01265m ~]$ cat /proc/version Linux version 2.6.18-194.17.4.el5 (mockbuild@builder10.centos.org) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-48)) #1 SMP Mon Oct 25 15:50:53 EDT 2010 ^[6]

[root@localhost ~]# [cognos@gl01265m ~]$ uname -a Linux gl01265m.gamesys.corp 2.6.18-194.17.4.el5 #1 SMP Mon Oct 25 15:50:53 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux ^[7]

Navigating

• CTRL-A = go to beginning of line
• CTRL-E = go to end of line
• CTRL-T = transpose two letters ^[8]

References

1. ↑ ^{1.0 1.1} Vivek Gite. (14 Mar 2006). "Howto: Linux Add User To Group" Retrieved 17 Jan 2011.
2. ↑ "untar multiple files"
3. ↑ http://www.computing.net/answers/programming/count-number-of-files-in-directory-/15868.html Retrieved 5 Apr 2011.
4. ↑ http://archives.unixforum.co.uk/showtopic147.html Retrieved 21 Jul 2011.
5. ↑ http://www.manpagez.com/man/1/killall/
6. ↑ Jeff Hunter. (18 Sep 2010). "Which Linux Version / Build / Distribution am I running?" Retrieved 17 Jan 2011.
7. ↑ (2 June 2008). http://fixunix.com/redhat/340630-32-bit-64-linux-version.html Retrieved 17 Jan 2011.
8. ↑ Mark D. Roth. "Command Line Stuff" Retrieved 12 May 2011.