Common CLI commands

• June 11, 2008
• 2 Comments
• Guides, Linux System Admin
• Posted by Gee

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 $HOME directory
	(cd dir && command)	Go to dir, execute command and return to current dir
	pushd .	Put current dir on stack so you can popd back to it
file searching
	alias l=’ls -l –color=auto’	quick dir listing
	ls -lrt	List files by date. See also newest and find_mm_yyyy
	ls /usr/bin | pr -T9 -W$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 cli && 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)
	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, 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
	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
	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). 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
	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 $((0x2dec))	Base conversion (hex to dec) ((shell arithmetic expansion))
	units -t ‘100m/9.72s’ ‘miles/hour’	Unit conversion (metric to imperial)
	units -t ‘500GB’ ‘GiB’	Unit conversion (SI to IEC prefixes)
	units -t ‘1 googol’	Definition lookup
	seq 100 | (tr ‘\n’ +; echo 0) | bc	Add a column of numbers. See also add and funcpy
calendar
	cal -3	Display a calendar
	cal 9 1752	Display a calendar for a particular month year
	date -d fri	What date is it this friday. See also day
	date –date=’25 Dec’ +%A	What day does xmas fall on, this year
	date –date=’@2147483647′	Convert seconds since the epoch (1970-01-01 UTC) to date
	TZ=’:America/Los_Angeles’ date	What time is it on West coast of US (use tzselect to find TZ)
	echo “mail -s ‘get the train’ [email protected] < /dev/null” | at 17:45	Email reminder
	echo “DISPLAY=$DISPLAY xmessage cooker” | at “NOW + 30 minutes”	Popup reminder
locales
	printf “%’d\n” 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 (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
	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
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
	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$COLUMNS	List processes by mem usage. See also ps_mem.py
	ps -C firefox-bin -L -o pid,tid,pcpu,state	List all threads for a particular process
	ps -p 1,2	List info for particular process IDs
	last reboot	Show system reboot history
	free -m	Show amount of (remaining) RAM (-m displays in MB)
	watch -n.1 ‘cat /proc/interrupts’	Watch changeable data continuously
system information (see also sysinfo) (‘#’ means root access is required)
	uname -a	Show kernel version and system architecture
	head -n1 /etc/issue	Show name and version of distribution
	cat /proc/partitions	Show all partitions registered on the system
	grep MemTotal /proc/meminfo	Show RAM total seen by the system
	grep “model name” /proc/cpuinfo	Show CPU(s) info
	lspci -tv	Show PCI info
	lsusb -tv	Show USB info
	mount | column -t	List mounted filesystems on the system (and align output)
#	dmidecode -q | less	Display SMBIOS/DMI information
#	smartctl -A /dev/sda | grep Power_On_Hours	How long has this disk (system) been powered on in total
#	hdparm -i /dev/sda	Show info about disk sda
#	hdparm -tT /dev/sda	Do a read speed test on disk sda
#	badblocks -s /dev/sda	Test for unreadable blocks on disk sda
interactive (see also linux keyboard shortcuts)
	readline	Line editor used by bash, python, bc, gnuplot, …
	screen	Virtual terminals with detach capability, …
	mc	Powerful file manager that can browse rpm, tar, ftp, ssh, …
	gnuplot	Interactive/scriptable graphing
	links	Web browser
	xdg-open http://www.pixelbeat.org/	open a file or url with the registered desktop application
miscellaneous
	alias hd=’od -Ax -tx1z -v’	Handy hexdump. (usage e.g.: hd /proc/self/cmdline | less)
	alias realpath=’readlink -f’	Canonicalize path. (usage e.g.: realpath ~/../$USER)
	set | grep $USER	Search current environment
	touch -c -t 0304050607 file	Set file timestamp (YYMMDDhhmm)

• Tags: Cli Commands, Linux, terminal, unix