Linux Commands

Linux, a cheating post

I didn't write this post. Rarely do I have need of Linux commands, but I have a list of them I reference occasionally. As part of my on-going, document-almost-everything I may ever need to reference campaign, I'm posting my list as my blog post for the day.
The original is at http://www.pixelbeat.org/cmdline.html and is posted much, much nicer than here. What follows is directly from their page (with a hearty thank-you to them for the years of use).

This is a linux command line reference for common operations.
Examples 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.
All these commands have been tested both on Fedora and Ubuntu.
See also more linux commands.

CommandDescription
apropos whatisShow commands pertinent to string. See also threadsafe
man -t ascii | ps2pdf - > ascii.pdfmake a pdf of a manual page

which commandShow full path name of command

time commandSee how long a command takes
time catStart stopwatch. Ctrl-d to stop. See also sw
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
alias l='ls -l --color=auto'quick dir listing
ls -lrtList files by date. See also newest and find_mm_yyyy
ls /usr/bin | pr -T9 -W$COLUMNSPrint in 9 columns to width of terminal

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 '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; 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
look referenceQuickly search (sorted) dictionary for prefix
grep --color reference /usr/share/dict/wordsHighlight occurances of regular expression in dictionary
archives and compression

gpg -c fileEncrypt file

gpg file.gpgDecrypt file

tar -c dir/ | bzip2 > dir.tar.bz2Make compressed 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/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 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/ 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 commandRun command on $HOST as $USER (default command=shell)
ssh -f -Y $USER@$HOSTNAME xeyesRun GUI command on $HOSTNAME as $USER

scp -p -r $USER@$HOST: file dir/Copy with permissions to $USER's home directory on $HOST

scp -c arcfour $USER@$LANHOST: bigfileUse faster crypto for local LAN. This might saturate GigE

ssh -g -L 8080:localhost:80 root@$HOSTForward connections to $HOSTNAME:8080 out to $HOST:80

ssh -R 1434:imap:143 root@$HOSTForward connections from $HOST:1434 in to imap:143

ssh-copy-id $USER@$HOST Install public key for $USER@$HOST for password-less log in
Of course, somewhere in here I need to put something that doesn't belong, but I know it's here. just ssh on your iPhone using the user 'mobile' (w/ default password 'alpine'). 

 wget (multi purpose download tool)
(cd dir/ && wget -nd -pHEKk http://www.pixelbeat.org/cmdline.html)Store local browsable version of a page to the current dir

wget -c http://www.example.com/large.fileContinue 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' | 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 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 eth0Show status of ethernet interface eth0

ethtool --change eth0 autoneg off speed 100 duplex fullManually set ethernet interface speed

iwconfig eth1Show status of wireless interface eth1

iwconfig eth1 rate 1Mb/s fixedManually set wireless interface speed
iwlist scanList wireless networks in range
ip link showList network interfaces

ip link set dev eth0 name wanRename interface eth0 to wan

ip link set dev eth0 upBring interface eth0 up (or down)
ip addr showList addresses for interfaces

ip addr add 1.2.3.4/24 brd + dev eth0Add (or del) ip and mask (255.255.255.0)
ip route showList routing table

ip route add default via 1.2.3.254Set default gateway to 1.2.3.254
host pixelbeat.orgLookup DNS ip address for name or vice versa
hostname -iLookup local ip address (equivalent to host `hostname`)
whois pixelbeat.orgLookup whois info for hostname or ip address
netstat -tuplList internet services on a system
netstat -tupList active connections to/from system
windows networking (Note samba is the package that provides all this windows specific networking support)
smbtreeFind windows machines. See also findsmb

nmblookup -A 1.2.3.4Find 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)
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 '1000{p;q}'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_hostsDelete a particular line

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
tr -s '[:blank:]' '\t' </proc/diskstats | cut -f4cut fields separated by blanks
history | wc -lCount lines
set operations (Note you can export LANG=C for speed. Also these assume no duplicate lines within a file)

sort file1 file2 | uniqUnion of unsorted files

sort file1 file2 | uniq -dIntersection of unsorted files

sort file1 file1 file2 | uniq -uDifference of unsorted files

sort file1 file2 | uniq -uSymmetric Difference of unsorted files

join -t'\0' -a1 -a2 file1 file2Union of sorted files

join -t'\0' file1 file2Intersection of sorted files

join -t'\0' -v2 file1 file2Difference of sorted files

join -t'\0' -v1 -v2 file1 file2Symmetric Difference of sorted files
math
echo '(1 + sqrt(5))/2' | bc -lQuick math (Calculate φ). See also bc
seq -f '4/%g' 1 2 99999 | paste -sd-+ | bc -lCalculate π the unix way
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
echo 'obase=16; ibase=10; 64206' | bcBase conversion (decimal to hexadecimal)
echo $((0x2dec))Base conversion (hex to dec) ((shell arithmetic expansion))
units -t '100m/9.58s' '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) | bcAdd a column of numbers. See also add and funcpy
calendar
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 -d '12:00 +1 day' +%d) = '01' ] || exitexit a script unless it's the last day of the month
date --date='25 Dec' +%AWhat 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' dateWhat time is it on west coast of US (use tzselect to find TZ)
date --date='TZ="America/Los_Angeles" 09:00 next Fri'What's the local time for 9AM next Friday on west coast US
locales
printf "%'d\n" 1234Print number with thousands grouping appropriate to locale
BLOCK_SIZE=\'1 ls -lUse locale thousands grouping in ls. See also l
echo "I live in `locale territory`"Extract info from locale database
LANG=en_IE.utf8 locale int_prefixLookup locale info for specific country. See also ccodes
locale -kc $(locale | sed -n 's/\(LC_.\{4,\}\)=.*/\1/p') | lessList fields available in locale database
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.qp > file.txtQuoted 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
CDs

gzip < /dev/cdrom > cdrom.iso.gzSave copy of data cdrom

mkisofs -V LABEL -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 -pad *.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
disk space (See also FSlint)
ls -lSrShow files by size, biggest last
du -s * | sort -k1,1rn | headShow top disk users in current dir. See also dutop
du -hs /home/* | sort -k1,1hSort paths by easy to interpret disk usage
df -hShow free space on mounted filesystems
df -iShow free inodes on mounted filesystems
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
> filetruncate data of file or create an empty file
monitoring/debugging
tail -f /var/log/messagesMonitor messages in a log file
strace -c ls >/dev/nullSummarise/profile system calls made by command
strace -f -e open ls >/dev/nullList system calls made by command
strace -f -e trace=write -e write=1,2 ls >/dev/nullMonitor what's written to stdout and stderr
ltrace -f -e getenv ls >/dev/nullList library calls made by command
lsof -p $$List paths that process id has open
lsof ~List processes that have specified path open
tcpdump not port 22Show network traffic except ssh. See also tcpdump_not_me
ps -e -o pid,args --forestList processes in a hierarchy
ps -e -o pcpu,cpu,nice,state,cputime,args --sort pcpu | sed '/^ 0.0 /d'List processes by % cpu usage
ps -e -orss=,args= | sort -b -k1,1n | pr -TW$COLUMNSList processes by mem (KB) usage. See also ps_mem.py
ps -C firefox-bin -L -o pid,tid,pcpu,stateList all threads for a particular process
ps -p 1,$$ -o etime=List elapsed wall time for particular process IDs
last rebootShow system reboot history
free -mShow amount of (remaining) RAM (-m displays in MB)
watch -n.1 'cat /proc/interrupts'Watch changeable data continuously
udevadm monitorMonitor udev events to help configure rules
system information (see also sysinfo) ('#' means root access is required)
uname -aShow kernel version and system architecture
head -n1 /etc/issueShow name and version of distribution
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
mount | column -tList mounted filesystems on the system (and align output)
grep -F capacity: /proc/acpi/battery/BAT0/infoShow state of cells in laptop battery
#dmidecode -q | lessDisplay SMBIOS/DMI information
#smartctl -A /dev/sda | grep Power_On_HoursHow long has this disk (system) been powered on in total
#hdparm -i /dev/sdaShow info about disk sda
#hdparm -tT /dev/sdaDo a read speed test on disk sda
#badblocks -s /dev/sdaTest for unreadable blocks on disk sda
interactive (see also linux keyboard shortcuts)
readlineLine editor used by bash, python, bc, gnuplot, ...
screenVirtual terminals with detach capability, ...
mcPowerful file manager that can browse rpm, tar, ftp, ssh, ...
gnuplotInteractive/scriptable graphing
linksWeb browser
xdg-open .open a file or url with the registered desktop application