This is a list of linux commands for common operations.
Note items marked with • are valid/safe to paste without modification into a terminal, so
you may want to keep a terminal window open while reading this so you can cut & paste.
Original site is

apropos wordShow commands pertinent to word. See also threadsafe
 which commandShow full path name of command
 time commandSee how long a command takes
time catStart stopwatch. Ctrl-d to stop. See also sw
nice infoRun a low priority command (info in this case)
renice 19 -p $$Make shell (script) low priority. Use for non interactive tasks
look prefixQuickly search (sorted) dictionary
grep --color expr...ion /usr/share/dict/wordsHighlight occurances of regular expression in dictionary
 gpg -c fileEncrypt file
 gpg file.gpgDecrypt file
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 $USERSearch current environment
ls /usr/bin | pr -T9 -W$COLUMNSPrint in 9 columns to width of terminal
 touch -c -t 0304050607 fileSet file timestamp (YYMMDDhhmm)
dir navigation
cd -Go to previous directory
cdGo 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
 gzip < /dev/cdrom > cdrom.iso.gzSave copy of data cdrom
 mkisofs -V NAME -r dir | gzip > cdrom.iso.gzCreate cdrom image from contents of dir
 mount -o loop cdrom.iso /mnt/dirMount the cdrom image at /mnt/dir (read only)
 cdrecord -v dev=/dev/cdrom blank=fastClear a CDRW
 gzip -dc cdrom.iso.gz | cdrecord -v dev=/dev/cdrom -Burn cdrom image (use dev=ATAPI -scanbus to confirm dev)
 cdparanoia -BRip audio tracks from CD to wav files in current dir
 cdrecord -v dev=/dev/cdrom -audio *.wavMake 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
 tar c dir/ | bzip2 > dir.tar.bz2Make archive of dir/
 bzip2 -dc dir.tar.bz2 | tar xExtract 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.bz2Make archive of subset of dir/ and below
 find dir/ -name '*.txt' | xargs cp -a --target-directory=dir_txt/ --parentsMake 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/hda | gzip | ssh user@remote 'dd of=hda.gz'Backup harddisk to remote machine
rsync (Use the --dry-run option for testing)
 rsync -P rsync:// fileOnly get diffs. Do multiple times for troublesome downloads
 rsync --bwlimit=1000 fromfile tofileLocally copy with rate limit. It's like nice for I/O
 rsync -az -e ssh --delete ~/public_html/'~/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
alias l='ls -l --color=auto'quick dir listing
ls -lrtList files by date. See also newest
 find -name '*.[ch]' | xargs grep -E 'expr'Search 'expr' in this dir and below. See also findrepo
 find -type f -print0 | xargs -r0 grep -F 'string'Search all regular files for 'string' in this dir and below
 find -maxdepth 1 -type f | xargs grep -F 'string'Search all regular files for 'string' in this dir
 find -maxdepth 1 -type d | while read dir; do echo $dir; echo cmd2; doneProcess each item with multiple commands (in while loop)
find -type f ! -perm -444Find files not readable by all (useful for web site)
find -type d ! -perm -111Find 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
networking (Note ifconfig, route, mii-tool, nslookup commands are obsolete)
ip link showList interfaces
 ethtool interfaceList interface status
 ip link set dev eth0 name wanRename eth0 to wan
 ip addr add brd + dev eth0Add ip and mask(
 ip link set dev interface upBring interface up (or down)
 ip route add default via default gateway to
tc qdisc add dev lo root handle 1:0 netem delay 20msecAdd 20ms latency to loopback device (for testing)
tc qdisc del dev lo rootRemove latency added above
host pixelbeat.orgLookup ip address for name or vice versa
hostname -iLookup local ip address (equivalent to host `hostname`)
netstat -tuplList internet services on a system
netstat -tupList active connections to/from system
wget (multi purpose download tool)
(cd cmdline && wget -nd -pHEKk Store local browsable version of a page to the current dir
 wget -c downloading a partially downloaded file
 wget -r -nd -np -l1 -A '*.jpg' a set of files to the current directory
 wget ftp://remote/file[1-9].iso/FTP supports globbing directly
wget -q -O- | grep 'a href' | headProcess output directly
 echo 'wget url' | at 01:00Download url at 1AM to current dir
 wget --limit-rate=20k urlDo a low priority download (limit to 20KB/s in this case)
 wget -nv --spider --force-html -i bookmarks.htmlCheck links in a file
 wget --mirror update a local copy of a site (handy from cron)
windows (note samba is the package that provides all this windows specific networking support)
smbtreeFind windows machines. See also findsmb
 nmblookup -A the windows (netbios) name associated with ip address
 smbclient -L windows_boxList shares on windows machine or samba server
 mount -t smbfs -o fmask=666,guest //windows_box/share /mnt/shareMount a windows share
 echo 'message' | smbclient -M windows_boxSend popup to windows machine (off by default in XP sp2)
echo '(1 + sqrt(5))/2' | bc -lQuick math (Calculate φ)
echo 'obase=16; ibase=10; 123' | bcBase conversion (decimal to hexadecimal)
echo $((0x2dec))Base conversion (hex to dec) ((shell arithmetic expansion))
echo 'pad=20; min=64; (100*10^6)/((pad+min)*8)' | bcMore complex (int) e.g. This shows max FastE packet rate
echo 'pad=20; min=64; print (100E6)/((pad+min)*8)' | pythonPython handles scientific notation
echo 'pad=20; plot [64:1518] (100*10**6)/((pad+x)*8)' | gnuplot -persistPlot FastE packet rate vs packet size
seq 100 | (tr '\n' +; echo 0) | bcAdd a column of numbers. See also add and funcpy
text manipulation (note sed uses stdin and stdout, so if you want to edit files, append <oldfile >newfile)
 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
 sed -n '1000p;1000q'Print 1000th line
 sed -n '10,20p;20q'Print lines 10 to 20
 sed -n 's/.*<[tT][iI][tT][lL][eE]>\(.*\)<\/[tT][iI][tT][lL][eE]>.*/\1/p;T;q'Extract title from HTML web page
 sort -t. -k1,1n -k2,2n -k3,3n -k4,4nSort IPV4 ip addresses
echo 'Test' | tr '[:lower:]' '[:upper:]'Case conversion
tr -dc '[:print:]' < /dev/urandomFilter non printable characters
grep 'processor' /proc/cpuinfo | wc -lCount lines
set operations (Note LANG=C is for speed) (Note also these assume no duplicate lines within a file)
 LANG=C sort file1 file2 | uniqUnion of unsorted files
 LANG=C sort file1 file2 | uniq -dIntersection of unsorted files
 LANG=C sort file1 file1 file2 | uniq -uDifference of unsorted files
 LANG=C sort file1 file2 | uniq -uSymmetric Difference of unsorted files
 LANG=C comm file1 file2 | sed 's/^\t*//'Union of sorted files
 LANG=C comm -12 file1 file2Intersection of sorted files
 LANG=C comm -13 file1 file2Difference of sorted files
 LANG=C comm -3 file1 file2 | sed 's/^\t*//'Symmetric Difference of sorted files
cal -3Display a calendar
cal 9 1752Display a calendar for a particular month year
date -d friWhat date is it this friday. See also day
date --date='25 Dec' +%AWhat day does xmas fall on, this year
date --date '1970-01-01 UTC 1234567890 seconds'Convert number of seconds since the epoch to a date
TZ=':America/Los_Angeles' dateWhat time is it on West coast of US (use tzselect to find TZ)
 echo "mail -s 'get the train' < /dev/null" | at 17:45Email reminder
echo "DISPLAY=$DISPLAY xmessage cooker" | at "NOW + 30 minutes"Popup reminder
printf "%'d\n" 1234Print number with thousands grouping appropriate to locale
echo "I live in `locale territory`"Extract info from locale database
locale | cut -d= -f1 | xargs locale -kc | lessList fields in locale database
LANG=en_IE.utf8 locale int_prefixLookup locale info for specific country. See also ccodes
disk space (See also FSlint)
ls -lSrShow files, biggest last
du -s * | sort -k1,1rn | headShow top disk users in current dir. See also dutop
df -hShow free disk space
df -iShow free inodes
fdisk -lShow disks partitions sizes and types (run as root)
rpm -q -a --qf '%10{SIZE}\t%{NAME}\n' | sort -k1,1nList all packages by installed size (Bytes) on rpm distros
dpkg-query -W -f='${Installed-Size;10}\t${Package}\n' | sort -k1,1nList all packages by installed size (KBytes) on deb distros
dd bs=1 seek=2TB if=/dev/null of=ext3.testCreate a large test file (taking no space). See also truncate
strace -c ls >/dev/nullSummarise/profile system calls made by command
strace -f -e open ls >/dev/nullList system calls made by command
ltrace -f -e getenv ls >/dev/nullList 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 22Show network traffic except ssh. See also tcpdump_not_me
ps -e -o pid,args --forestList 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$COLUMNSList processes by mem usage. See also
ps -C firefox-bin -L -o pid,tid,pcpu,stateList all threads for a particular process
ps -p 1,2List info for particular process IDs
last rebootShow system reboot history.
free -mShow amount of (remaining) RAM (-m displays in MB)
watch -n1 'cat /proc/interrupts'Watch changeable data continuously
System information (see also sysinfo)
 hdparm -i /dev/hdaShow info about disk hda
 hdparm -tT /dev/hdaDo a read speed test on disk hda
 badblocks -s /dev/hdaTest for unreadable blocks on disk hda
mount | column -tShow mounted filesystems on the system (and align output)
cat /proc/partitionsShow all partitions registered on the system
grep MemTotal /proc/meminfoShow RAM total seen by the system
grep "model name" /proc/cpuinfoShow CPU(s) info
lspci -tvShow PCI info
lsusb -tvShow USB info
recode (Obsoletes iconv, dos2unix, unix2dos)
recode -l | lessShow available conversions (aliases on each line)
 recode windows-1252.. file_to_change.txtWindows "ansi" to local charset (auto does CRLF conversion)
 recode utf-8/CRLF.. file_to_change.txtWindows utf8 to local charset
 recode iso-8859-15..utf8 file_to_change.txtLatin9 (western europe) to utf8
 recode ../b64 < file.txt > file.b64Base64 encode
 recode /qp.. < file.txt > file.qpQuoted printable decode
 recode ..HTML < file.txt > file.htmlText to HTML
recode -lf windows-1252 | grep euroLookup table of characters
echo -n 0x80 | recode latin-9/x1..dumpShow what a code represents in latin-9 charmap
echo -n 0x20AC | recode ucs-2/x2..latin-9/xShow latin-9 encoding
echo -n 0x20AC | recode ucs-2/x2..utf-8/xShow utf-8 encoding
mcPowerful filemanager that can browse rpm, tar, ftp, ssh, ...
screenVirtual terminals with detach capability, ...
linksWeb browser
gnuplotInteractive/scriptable graphing
octaveMatlab like environment