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Linux Commands Help PDF  | Print |  E-mail
 Command   Description
 


   


apropos word  Show commands pertinent to word
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 (info in this case)
renice 19 -p $$  Make shell (script) low priority. Use for non interactive tasks
look reference  Quickly search (sorted) dictionary for prefix
grep --color reference /usr/share/dict/words  Highlight occurances of regular expression in dictionary
gpg -c file  Encrypt file
gpg file.gpg  Decrypt 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 $USER  Search current environment
ls /usr/bin | pr -T9 -W$COLUMNS  Print in 9 columns to width of terminal
touch -c -t 0304050607 file  Set file timestamp (YYMMDDhhmm)
 
   
 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
 
   
 CDs
    
gzip < /dev/cdrom > cdrom.iso.gz  Save copy of data cdrom
mkisofs -V NAME -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
 
   
 archives
    
tar c dir/ | bzip2 > dir.tar.bz2  Make 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'B  Backup harddisk to remote machine
 
   
 rsync (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
 
   
 file searching
    
alias l='ls -l --color=auto'  quick dir listing
ls -lrt  List files by date. See also newest and find_mm_yyyy
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
 
   
 networking (Note ifconfig, route, mii-tool, nslookup commands are obsolete)
    
ip link show  List interfaces
ethtool interface  List interface status
ip link set dev eth0 name wan  Rename eth0 to wan
ip addr add 1.2.3.4/24 brd + dev eth0
  Add ip and mask(255.255.255.0)
ip link set dev interface up  Bring interface up (or down)
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 ip address for name or vice versa
hostname -i  Lookup local ip address (equivalent to host `hostname`)
netstat -tupl  List internet services on a system
netstat -tup
  List active connections to/from system
 
   
 wget (multi purpose download tool)
    
(cd cmdline && 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)
 
   
 windows (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)
 
   
 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/9.74s' '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
 
   
 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/.*<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
grep 'processor' /proc/cpuinfo | wc -l  Count lines
 
   
 set operations (Note LANG=C is for speed)
    
LANG=C sort file1 file2 | uniq
  Union of unsorted files
LANG=C sort file1 file2 | uniq -d  Intersection of unsorted files
LANG=C sort file1 file1 file2 | uniq -u  Difference of unsorted files
LANG=C sort file1 file2 | uniq -u  Symmetric Difference of unsorted files
LANG=C comm file1 file2 | sed 's/^\t*//'  Union of sorted files
LANG=C comm -12 file1 file2  Intersection of sorted files
LANG=C comm -13 file1 file2  Difference of sorted files
LANG=C comm -3 file1 file2 | sed 's/^\t*//'  Symmetric Difference of sorted files
 
   
 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 --date='25 Dec' +%A  What day does xmas fall on, this year
date --date '1970-01-01 UTC 2147483647 seconds'  Convert number of seconds since the epoch to a 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' This e-mail address is being protected from spam bots, you need JavaScript enabled to view it < /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
locale | cut -d= -f1 | xargs locale -kc | less  List fields in locale database
LANG=en_IE.utf8 locale int_prefix  Lookup locale info for specific country
 
   
disk space (See also FSlint)
 
ls -lSr  Show files, biggest last
du -s * | sort -k1,1rn | head  Show top disk users in current dir
df -h  Show free disk space
df -i
  Show free inodes
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)
 
   
 monitoring/debugging
    
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
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 -n1 'cat /proc/interrupts'  Watch changeable data continuously
 
   
 System information (see also sysinfo) ('#' means root access is required)
    
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
mount | column -t  Show mounted filesystems on the system (and align output)
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
 
   
 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
 
   
 interactive
    
mc
  Powerful file manager that can browse rpm, tar, ftp, ssh, ...
screen  Virtual terminals with detach capability, ...
links  Web browser
gnuplot  Interactive/scriptable graphing
octave  Matlab like environment
 
   
 [Sourcre: http://www.pixelbeat.org/cmdline.html ]