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.
Command
Description
•
apropos whatis
Show commands pertinent to string. See also threadsafe
•
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. See also sw
•
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 $HOME directory
(cd dir && command)
Go to dir, execute command and return to current dir
•
pushd .
Put current dir on stack so you can popd back to it
file searching
•
alias l='ls -l --color=auto'
quick dir listing
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ls -lrt
List files by date. See also newest and find_mm_yyyy
•
ls /usr/bin | pr -T9 -W$COLUMNS
Print in 9 columns to width of terminal
find -name '*.[ch]' | xargs grep -E 'expr'
Search 'expr' in this dir and below. 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; 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 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.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)
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tc qdisc del dev lo root
Remove latency added above
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host pixelbeat.org
Lookup DNS ip address for name or vice versa
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hostname -i
Lookup local ip address (equivalent to host `hostname`)
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whois pixelbeat.org
Lookup whois info for hostname or ip address
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netstat -tupl
List internet services on a system
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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
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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>.*/\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
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tr -dc '[:print:]' < /dev/urandom
Filter non printable characters
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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 -t'\0' -a1 -a2 file1 file2
Union of sorted files
join -t'\0' file1 file2
Intersection of sorted files
join -t'\0' -v2 file1 file2
Difference of sorted files
join -t'\0' -v1 -v2 file1 file2
Symmetric Difference of sorted files
math
•
echo '(1 + sqrt(5))/2' | bc -l
Quick math (Calculate φ). See also bc
•
echo 'pad=20; min=64; (100*10^6)/((pad+min)*8)' | bc
More complex (int) e.g. This shows max FastE packet rate
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echo 'pad=20; min=64; print (100E6)/((pad+min)*8)' | python
Python handles scientific notation
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echo 'pad=20; plot [64:1518] (100*10**6)/((pad+x)*8)' | gnuplot -persist
Plot FastE packet rate vs packet size
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echo 'obase=16; ibase=10; 64206' | bc
Base conversion (decimal to hexadecimal)
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echo $((0x2dec))
Base conversion (hex to dec) ((shell arithmetic expansion))
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units -t '100m/9.58s' 'miles/hour'
Unit conversion (metric to imperial)
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units -t '500GB' 'GiB'
Unit conversion (SI to IEC prefixes)
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units -t '1 googol'
Definition lookup
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seq 100 | (tr '\n' +; echo 0) | bc
Add a column of numbers. See also add and funcpy
calendar
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cal -3
Display a calendar
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cal 9 1752
Display a calendar for a particular month year
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date -d fri
What date is it this friday. See also day
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[ $(date -d "tomorrow" +%d) = "01" ] || exit
exit a script unless it's the last day of the month
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date --date='25 Dec' +%A
What day does xmas fall on, this year
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date --date='@2147483647'
Convert seconds since the epoch (1970-01-01 UTC) to date
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TZ=':America/Los_Angeles' date
What time is it on West coast of US (use tzselect to find TZ)
echo "mail -s 'get the train' P@draigBrady.com < /dev/null" | at 17:45
Email reminder
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echo "DISPLAY=$DISPLAY xmessage cooker" | at "NOW + 30 minutes"
Popup reminder
locales
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printf "%'d\n" 1234
Print number with thousands grouping appropriate to locale
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BLOCK_SIZE=\'1 ls -l
get ls to do thousands grouping appropriate to locale
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echo "I live in `locale territory`"
Extract info from locale database
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LANG=en_IE.utf8 locale int_prefix
Lookup locale info for specific country. See also ccodes
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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.b64
Base64 encode
recode /qp.. <> file.qp
Quoted printable decode
recode ..HTML <> file.html
Text to HTML
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recode -lf windows-1252 | grep euro
Lookup table of characters
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echo -n 0x80 | recode latin-9/x1..dump
Show what a code represents in latin-9 charmap
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echo -n 0x20AC | recode ucs-2/x2..latin-9/x
Show latin-9 encoding
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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 (See also FSlint)
•
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
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df -i
Show free inodes on mounted filesystems
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fdisk -l
Show disks partitions sizes and types (run as root)
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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
monitoring/debugging
•
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
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lsof -p $$
List paths that process id has open
•
lsof ~
List processes that have specified path open
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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
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ps -e -o pcpu,cpu,nice,state,cputime,args --sort pcpu | sed '/^ 0.0 /d'
List processes by % cpu usage
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ps -e -orss=,args= | sort -b -k1,1n | pr -TW$COLUMNS
List processes by mem usage. See also ps_mem.py
•
ps -C firefox-bin -L -o pid,tid,pcpu,state
List all threads for a particular process
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ps -p 1,2
List info for particular process IDs
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last reboot
Show system reboot history
•
free -m
Show amount of (remaining) RAM (-m displays in MB)
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watch -n.1 'cat /proc/interrupts'
Watch changeable data continuously
system information (see also sysinfo) ('#' means root access is required)
•
uname -a
Show kernel version and system architecture
•
head -n1 /etc/issue
Show name and version of distribution
•
cat /proc/partitions
Show all partitions registered on the system
•
grep MemTotal /proc/meminfo
Show RAM total seen by the system
•
grep "model name" /proc/cpuinfo
Show CPU(s) info
•
lspci -tv
Show PCI info
•
lsusb -tv
Show USB info
•
mount | column -t
List mounted filesystems on the system (and align output)
•
grep -F capacity: /proc/acpi/battery/BAT0/info
Show state of cells in laptop battery
#
dmidecode -q | less
Display SMBIOS/DMI information
#
smartctl -A /dev/sda | grep Power_On_Hours
How long has this disk (system) been powered on in total
#
hdparm -i /dev/sda
Show info about disk sda
#
hdparm -tT /dev/sda
Do a read speed test on disk sda
#
badblocks -s /dev/sda
Test for unreadable blocks on disk sda
interactive (see also linux keyboard shortcuts)
•
Line editor used by bash, python, bc, gnuplot, ...
•
Virtual terminals with detach capability, ...
•
Powerful file manager that can browse rpm, tar, ftp, ssh, ...
•
Interactive/scriptable graphing
•
links
Web browser
•
xdg-open http://www.pixelbeat.org/
open a file or url with the registered desktop application
miscellaneous
•
alias hd='od -Ax -tx1z -v'
Handy hexdump. (usage e.g.: • hd /proc/self/cmdline | less)
•
alias realpath='readlink -f'
Canonicalize path. (usage e.g.: • realpath ~/../$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/
