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LINUX COMMAND LINE REFERENCE FOR COMMON OPERATIONS

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 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/

System Message: WARNING/2 (data/linux-command-line-reference.txt, line 64); backlink

Inline emphasis start-string without end-string.

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:

Download url at 1AM to current dir:

echo 'wget url' | at 01:00

Do a low priority download (limit to 20KB/s in this case):

wget --limit-rate=20k url

Check links in a file:

wget -nv --spider --force-html -i bookmarks.html

Efficiently update a local copy of a site (handy from cron):

wget --mirror http://www.example.com/

networking (Note ifconfig, route, mii-tool, nslookup commands are obsolete):

Show status of ethernet interface eth0
ethtool eth0

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

iwconfig eth1   Show status of wireless interface eth1
iwconfig eth1 rate 1Mb/s fixed  Manually set wireless interface speed

List wireless networks in range:

iwlist scan

List network interfaces:

ip link show

Rename interface eth0 to wan:

ip link set dev eth0 name wan

Bring interface eth0 up (or down):

ip link set dev eth0 up

List addresses for interfaces:

ip addr show

Add (or del) ip and mask (255.255.255.0):

ip addr add 1.2.3.4/24 brd + dev eth0

List routing table:

ip route show

Set default gateway to 1.2.3.254:

ip route add default via 1.2.3.254

Add 20ms latency to loopback device (for testing):

tc qdisc add dev lo root handle 1:0 netem delay 20msec

Remove latency added above:

tc qdisc del dev lo root

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. 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_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 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 -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 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/9.58s' '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) | bc Add a column of numbers. See also add and funcpy

cal -3

cal 9 1752

date -d fri

[ $(date -d "tomorrow" +%d) = "01" ] || exit

date --date='25 Dec' +%A

date --date='@2147483647'

TZ='America/Los_Angeles' date   What 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
echo "mail -s 'get the train' P@draigBrady.com < /dev/null" | at 17:45  Email reminder
echo "DISPLAY=$DISPLAY xmessage cooker" | at "NOW + 30 minutes" Popup reminder

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