Linux/Unix – Linux command line reference for common operations..

This is a Linux command line reference for common operations. All these commands have been tested both on Red Hat and Debian distros.

Command

Description

 

apropos whatis

Show commands pertinent to string.

 

man -t man | ps2pdf – > man.pdf

make a pdf of a manual page

 

which command

Show full path name of command

 

time command

See how long a command takes

 

time cat

Start stopwatch. Ctrl-d to stop.

 

nice info

Run a low priority command (The “info” reader in this case)

 

renice 19 -p $$

Make shell (script) low priority. Use for non interactive tasks

dir navigation

 

cd –

Go to previous directory

 

cd

Go to $HOME directory

 

(cd dir && command)

Go to dir, execute command and return to current dir

 

pushd .

Put current dir on stack so you can popd back to it

file searching

 

alias l=’ls -l –color=auto’

quick dir listing

 

ls -lrt

List files by date.

 

ls /usr/bin | pr -T9 -W$COLUMNS

Print in 9 columns to width of terminal

 

find -name ‘*.[ch]’ | xargs grep -E ‘expr’

Search ‘expr’ in this dir and below.

 

find -type f -print0 | xargs -r0 grep -F ‘example’

Search all regular files for ‘example’ in this dir and below

 

find -maxdepth 1 -type f | xargs grep -F ‘example’

Search all regular files for ‘example’ in this dir

 

find -maxdepth 1 -type d | while read dir; do echo $dir; echo cmd2; done

Process each item with multiple commands (in while loop)

 

find -type f ! -perm -444

Find files not readable by all (useful for web site)

 

find -type d ! -perm -111

Find dirs not accessible by all (useful for web site)

 

locate -r ‘file[^/]*.txt’

Search cached index for names. This re is like glob *file*.txt

 

look reference

Quickly search (sorted) dictionary for prefix

 

grep –color reference /usr/share/dict/words

Highlight occurances of regular expression in dictionary

archives and compression

 

gpg -c file

Encrypt file

 

gpg file.gpg

Decrypt file

 

tar -c dir/ | bzip2 > dir.tar.bz2

Make compressed archive of dir/

 

bzip2 -dc dir.tar.bz2 | tar -x

Extract archive (use gzip instead of bzip2 for tar.gz files)

 

tar -c dir/ | gzip | gpg -c | ssh user@remote ‘dd of=dir.tar.gz.gpg’

Make encrypted archive of dir/ on remote machine

 

find dir/ -name ‘*.txt’ | tar -c –files-from=- | bzip2 > dir_txt.tar.bz2

Make archive of subset of dir/ and below

 

find dir/ -name ‘*.txt’ | xargs cp -a –target-directory=dir_txt/ –parents

Make copy of subset of dir/ and below

 

( tar -c /dir/to/copy ) | ( cd /where/to/ && tar -x -p )

Copy (with permissions) copy/ dir to /where/to/ dir

 

( cd /dir/to/copy && tar -c . ) | ( cd /where/to/ && tar -x -p )

Copy (with permissions) contents of copy/ dir to /where/to/

 

( tar -c /dir/to/copy ) | ssh -C user@remote ‘cd /where/to/ && tar -x -p’

Copy (with permissions) copy/ dir to remote:/where/to/ dir

 

dd bs=1M if=/dev/sda | gzip | ssh user@remote ‘dd of=sda.gz’

Backup harddisk to remote machine

rsync (Network efficient file copier: Use the –dry-run option for testing)

 

rsync -P rsync://rsync.server.com/path/to/file file

Only get diffs. Do multiple times for troublesome downloads

 

rsync –bwlimit=1000 fromfile tofile

Locally copy with rate limit. It’s like nice for I/O

 

rsync -az -e ssh –delete ~/public_html/ remote.com:’~/public_html’

Mirror web site (using compression and encryption)

 

rsync -auz -e ssh remote:/dir/ . && rsync -auz -e ssh . remote:/dir/

Synchronize current directory with remote one

ssh (Secure SHell)

 

ssh $USER@$HOST command

Run command on $HOST as $USER (default command=shell)

 

ssh -f -Y $USER@$HOSTNAME xeyes

Run GUI command on $HOSTNAME as $USER

 

scp -p -r $USER@$HOST: file dir/

Copy with permissions to $USER’s home directory on $HOST

 

ssh -g -L 8080:localhost:80 root@$HOST

Forward connections to $HOSTNAME:8080 out to $HOST:80

 

ssh -R 1434:imap:143 root@$HOST

Forward connections from $HOST:1434 in to imap:143

wget (multi purpose download tool)

 

(cd cli && wget -nd -pHEKk http://www. example.com /cmdline.html)

Store local browsable version of a page to the current dir

 

wget -c http://www.example.com/large.file

Continue downloading a partially downloaded file

 

wget -r -nd -np -l1 -A ‘*.jpg’ http://www.example.com/dir/

Download a set of files to the current directory

 

wget ftp://remote/file[1-9].iso/

FTP supports globbing directly

 

wget -q -O- http://www.pixelbeat.org/timeline.html | grep ‘a href’ | head

Process output directly

 

echo ‘wget url’ | at 01:00

Download url at 1AM to current dir

 

wget –limit-rate=20k url

Do a low priority download (limit to 20KB/s in this case)

 

wget -nv –spider –force-html -i bookmarks.html

Check links in a file

 

wget –mirror http://www.example.com/

Efficiently update a local copy of a site (handy from cron)

networking (Note ifconfig, route, mii-tool, nslookup commands are obsolete)

 

ethtool eth0

Show status of ethernet interface eth0

 

ethtool –change eth0 autoneg off speed 100 duplex full

Manually set ethernet interface speed

 

iwconfig eth1

Show status of wireless interface eth1

 

iwconfig eth1 rate 1Mb/s fixed

Manually set wireless interface speed

 

iwlist scan

List wireless networks in range

 

ip link show

List network interfaces

 

ip link set dev eth0 name wan

Rename interface eth0 to wan

 

ip link set dev eth0 up

Bring interface eth0 up (or down)

 

ip addr show

List addresses for interfaces

 

ip addr add 1.2.3.4/24 brd + dev eth0

Add (or del) ip and mask (255.255.255.0)

 

ip route show

List routing table

 

ip route add default via 1.2.3.254

Set default gateway to 1.2.3.254

 

tc qdisc add dev lo root handle 1:0 netem delay 20msec

Add 20ms latency to loopback device (for testing)

 

tc qdisc del dev lo root

Remove latency added above

 

host pixelbeat.org

Lookup DNS ip address for name or vice versa

 

hostname -i

Lookup local ip address (equivalent to host `hostname`)

 

whois pixelbeat.org

Lookup whois info for hostname or ip address

 

netstat -tupl

List internet services on a system

 

netstat -tup

List active connections to/from system

windows networking (Note samba is the package that provides all this windows specific networking support)

smbtree

Find windows machines. See also findsmb

 

nmblookup -A 1.2.3.4

Find the windows (netbios) name associated with ip address

 

smbclient -L windows_box

List shares on windows machine or samba server

 

mount -t smbfs -o fmask=666,guest //windows_box/share /mnt/share

Mount a windows share

 

echo ‘message’ | smbclient -M windows_box

Send popup to windows machine (off by default in XP sp2)

text manipulation (Note sed uses stdin and stdout. Newer versions support inplace editing with the -i option)

 

sed ‘s/string1/string2/g’

Replace string1 with string2

 

sed ‘s/(.*)1/12/g’

Modify anystring1 to anystring2

 

sed ‘/ *#/d; /^ *$/d’

Remove comments and blank lines

 

sed ‘:a; /$/N; s/n//; ta’

Concatenate lines with trailing

 

sed ‘s/[ t]*$//’

Remove trailing spaces from lines

 

sed ‘s/([`”$\])/1/g’

Escape shell metacharacters active within double quotes

 

seq 10 | sed “s/^/      /; s/ *(.{7,})/1/”

Right align numbers

 

sed -n ‘1000p;1000q’

Print 1000th line

 

sed -n ‘10,20p;20q’

Print lines 10 to 20

 

sed -n ‘s/.*<title>(.*)</title>.*/1/ip;T;q’

Extract title from HTML web page

 

sed -i 42d ~/.ssh/known_hosts

Delete a particular line

 

sort -t. -k1,1n -k2,2n -k3,3n -k4,4n

Sort IPV4 ip addresses

 

echo ‘Test’ | tr ‘[:lower:]’ ‘[:upper:]’

Case conversion

 

tr -dc ‘[:print:]’ < /dev/urandom

Filter non printable characters

 

history | wc -l

Count lines

set operations (Note you can export LANG=C for speed. Also these assume no duplicate lines within a file)

 

sort file1 file2 | uniq

Union of unsorted files

 

sort file1 file2 | uniq -d

Intersection of unsorted files

 

sort file1 file1 file2 | uniq -u

Difference of unsorted files

 

sort file1 file2 | uniq -u

Symmetric Difference of unsorted files

 

join -a1 -a2 file1 file2

Union of sorted files

 

join file1 file2

Intersection of sorted files

 

join -v2 file1 file2

Difference of sorted files

 

join -v1 -v2 file1 file2

Symmetric Difference of sorted files

math

 

echo ‘(1 + sqrt(5))/2’ | bc -l

Quick math (Calculate φ).

 

echo ‘pad=20; min=64; (100*10^6)/((pad+min)*8)’ | bc

More complex (int) e.g. This shows max FastE packet rate

 

echo ‘pad=20; min=64; print (100E6)/((pad+min)*8)’ | python

Python handles scientific notation

 

echo ‘pad=20; plot [64:1518] (100*10**6)/((pad+x)*8)’ | gnuplot -persist

Plot FastE packet rate vs packet size

 

echo ‘obase=16; ibase=10; 64206’ | bc

Base conversion (decimal to hexadecimal)

 

echo $((0x2dec))

Base conversion (hex to dec) ((shell arithmetic expansion))

 

units -t ‘100m/9.69s’ ‘miles/hour’

Unit conversion (metric to imperial)

 

units -t ‘500GB’ ‘GiB’

Unit conversion (SI to IEC prefixes)

 

units -t ‘1 googol’

Definition lookup

 

seq 100 | (tr ‘n’ +; echo 0) | bc

Add a column of numbers.

calendar

 

cal -3

Display a calendar

 

cal 9 1752

Display a calendar for a particular month year

 

date -d fri

What date is it this friday.

 

[ $(date -d “tomorrow” +%d) = “01” ] || exit

exit a script unless it’s the last day of the month

 

date –date=’25 Dec’ +%A

What day does xmas fall on, this year

 

date –date=’@2147483647′

Convert seconds since the epoch (1970-01-01 UTC) to date

 

TZ=’:America/Los_Angeles’ date

What time is it on West coast of US (use tzselect to find TZ)

 

echo “mail -s ‘get the train’ P@draigBrady.com < /dev/null” | at 17:45

Email reminder

 

echo “DISPLAY=$DISPLAY xmessage cooker” | at “NOW + 30 minutes”

Popup reminder

locales

 

printf “%’dn” 1234

Print number with thousands grouping appropriate to locale

 

BLOCK_SIZE=’1 ls -l

get ls to do thousands grouping appropriate to locale

 

echo “I live in `locale territory`”

Extract info from locale database

 

LANG=en_IE.utf8 locale int_prefix

Lookup locale info for specific country. See also ccodes

 

locale | cut -d= -f1 | xargs locale -kc | less

List fields available in locale database

recode (Obsoletes iconv, dos2unix, unix2dos)

 

recode -l | less

Show available conversions (aliases on each line)

 

recode windows-1252.. file_to_change.txt

Windows “ansi” to local charset (auto does CRLF conversion)

 

recode utf-8/CRLF.. file_to_change.txt

Windows utf8 to local charset

 

recode iso-8859-15..utf8 file_to_change.txt

Latin9 (western europe) to utf8

 

recode ../b64 < file.txt > file.b64

Base64 encode

 

recode /qp.. < file.txt > file.qp

Quoted printable decode

 

recode ..HTML < file.txt > file.html

Text to HTML

 

recode -lf windows-1252 | grep euro

Lookup table of characters

 

echo -n 0x80 | recode latin-9/x1..dump

Show what a code represents in latin-9 charmap

 

echo -n 0x20AC | recode ucs-2/x2..latin-9/x

Show latin-9 encoding

 

echo -n 0x20AC | recode ucs-2/x2..utf-8/x

Show utf-8 encoding

CDs

 

gzip < /dev/cdrom > cdrom.iso.gz

Save copy of data cdrom

 

mkisofs -V LABEL -r dir | gzip > cdrom.iso.gz

Create cdrom image from contents of dir

 

mount -o loop cdrom.iso /mnt/dir

Mount the cdrom image at /mnt/dir (read only)

 

cdrecord -v dev=/dev/cdrom blank=fast

Clear a CDRW

 

gzip -dc cdrom.iso.gz | cdrecord -v dev=/dev/cdrom –

Burn cdrom image (use dev=ATAPI -scanbus to confirm dev)

 

cdparanoia -B

Rip audio tracks from CD to wav files in current dir

 

cdrecord -v dev=/dev/cdrom -audio *.wav

Make audio CD from all wavs in current dir (see also cdrdao)

 

oggenc –tracknum=’track’ track.cdda.wav -o ‘track.ogg’

Make ogg file from wav file

Disk space

 

ls -lSr

Show files by size, biggest last

 

du -s * | sort -k1,1rn | head

Show top disk users in current dir. See also dutop

 

df -h

Show free space on mounted filesystems

 

df -i

Show free inodes on mounted filesystems

 

fdisk -l

Show disks partitions sizes and types (run as root)

 

rpm -q -a –qf ‘%10{SIZE}t%{NAME}n’ | sort -k1,1n

List all packages by installed size (Bytes) on rpm distros

 

dpkg-query -W -f=’${Installed-Size;10}t${Package}n’ | sort -k1,1n

List all packages by installed size (KBytes) on deb distros

 

dd bs=1 seek=2TB if=/dev/null of=ext3.test

Create a large test file (taking no space). See also truncate

 

> file

truncate data of file or create an empty file

 
 

tail -f /var/log/messages

Monitor messages in a log file

 

strace -c ls >/dev/null

Summarise/profile system calls made by command

 

strace -f -e open ls >/dev/null

List system calls made by command

 

ltrace -f -e getenv ls >/dev/null

List library calls made by command

 

lsof -p $$

List paths that process id has open

 

lsof ~

List processes that have specified path open

 

tcpdump not port 22

Show network traffic except ssh. See also tcpdump_not_me

 

ps -e -o pid,args –forest

List processes in a hierarchy

 

ps -e -o pcpu,cpu,nice,state,cputime,args –sort pcpu | sed ‘/^ 0.0 /d’

List processes by % cpu usage

 

ps -e -orss=,args= | sort -b -k1,1n | pr -TW$COLUMNS

List processes by mem usage.

 

ps -C firefox-bin -L -o pid,tid,pcpu,state

List all threads for a particular process

 

ps -p 1,2

List info for particular process IDs

 

last reboot

Show system reboot history

 

free -m

Show amount of (remaining) RAM (-m displays in MB)

 

watch -n.1 ‘cat /proc/interrupts’

Watch changeable data continuously

System information (‘#’ means root access is required)

 

uname -a

Show kernel version and system architecture

 

head -n1 /etc/issue

Show name and version of distribution

 

cat /proc/partitions

Show all partitions registered on the system

 

grep MemTotal /proc/meminfo

Show RAM total seen by the system

 

grep “model name” /proc/cpuinfo

Show CPU(s) info

 

lspci -tv

Show PCI info

 

lsusb -tv

Show USB info

 

mount | column -t

List mounted filesystems on the system (and align output)

 

grep -F capacity: /proc/acpi/battery/BAT0/info

Show state of cells in laptop battery

#

dmidecode -q | less

Display SMBIOS/DMI information

#

smartctl -A /dev/sda | grep Power_On_Hours

How long has this disk (system) been powered on in total

#

hdparm -i /dev/sda

Show info about disk sda

#

hdparm -tT /dev/sda

Do a read speed test on disk sda

#

badblocks -s /dev/sda

Test for unreadable blocks on disk sda

interactive

 

readline

Line editor used by bash, python, bc, gnuplot, …

 

screen

Virtual terminals with detach capability, …

 

mc

Powerful file manager that can browse rpm, tar, ftp, ssh, …

 

gnuplot

Interactive/scriptable graphing

 

links

Web browser

 

xdg-open http://www.pixelbeat.org/

open a file or url with the registered desktop application

miscellaneous

 

alias hd=’od -Ax -tx1z -v’

Handy hexdump. (usage e.g.: • hd /proc/self/cmdline | less)

 

alias realpath=’readlink -f’

Canonicalize path. (usage e.g.: • realpath ~/../$USER)

 

set | grep $USER

Search current environment

 

touch -c -t 0304050607 file

Set file timestamp (YYMMDDhhmm)

 

python -m SimpleHTTPServer

Serve current directory tree at http://$HOSTNAME:8000/

 

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About msotela

This blog is for anyone who wants to access the power of a Linux system as a systems administrator or user. You may be a Linux enthusiast, a Linux professional, or possibly a computer professional who is increasingly finding the Windows systems in your data center supplanted by Linux boxes.

Posted on March 15, 2009, in Unix/Linux and tagged , , . Bookmark the permalink. Leave a comment.

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