I am glad that you are here! I started working on bioinformatics four years ago (recently switched to cloud computing), and was amazed by those single-word bash commands which are much faster than my dull scripts, so much time can be saved through knowing command-line shortcuts and scripting. Not all the code here is oneliner (if the ';' counts..), but i put effort on making them brief and fast. I am mainly using Ubuntu, RedHat and Linux Mint, sorry if the commands dont work on your system.
This blog will focus on simple bash commands for parsing data; some of them are for Linux system maintenance. I apologize that there are no detailed citation for all the commands, but they are probably from dear Google and Stackoverflow.
English and bash are not my first language, so... correct me anytime, thank you!
And if you know any cool command that are not included here, Please Teach Me.
In case you would like to check and vote up my questions on Stackoverflow, here's my page: http://stackoverflow.com/users/4290753/once
Here's a more stylish version of Bash-Oneliner~ http://onceupon.github.io/Bash-Oneliner/
grep -o 'S.*'
grep -o -P '(?<=w1).*(?=w2)'
grep -o '[0-9]*'
grep -v bbo filename
grep -v '^#' file.txt
grep "$boo" filename
#remember to quote the variable!
grep -m 1 bbo filename
grep -c bbo filename
grep -i "bbo" filename
grep -o bbo filename
grep --color bbo filename
grep -R bbo /path/to/directory
or
grep -r bbo /path/to/directory
grep -Rh bbo /path/to/directory
or
grep -rh bbo /path/to/directory
or only list filename with match
grep -rl bbo /path/to/directory
grep 'A\|B\|C\|D'
grep 'A.*B'
grep -f fileA fileB
grep $'\t'
$echo "$long_str"|grep -q "$short_str"
if [ $? -eq 0 ]; then echo 'found'; fi
#grep -q will output 0 if match found
#remember to add space between []!
grep -oP '\(\K[^\)]+'
grep -o -w "\w\{10\}\-R\w\{1\}"
# \w word character [0-9a-zA-Z_] \W not word character
http://www.cyberciti.biz/faq/grep-regular-expressions/
sed 1d filename
sed 1,100d filename
sed "/bbo/d" filename
- case insensitive:
sed "/bbo/Id" filename
sed -E '/^.{5}[^2]/d'
#aaaa2aaa (you can stay)
#aaaa1aaa (delete!)
sed -i "/bbo/d" filename
e.g. add >$i to the first line (to make a FASTA file)
sed "1i >$i"
# notice the double quotes! in other examples, you can use a single quote, but here, no way!
# '1i' means insert to first line
sed '/^\s*$/d'
or
sed '/^$/d'
sed '$d'
sed -i '$ s/.$//' filename
sed '$s/$/]/' filename
sed '$a\'
sed -e 's/^/bbo/' file
sed -e 's/$/\}\]/' filename
sed 's/.\{4\}/&\n/g'
sed -s '$a,' *.json > all.json
sed 's/A/B/g' filename
sed "s/aaa=.*/aaa=\/my\/new\/path/g"
sed -n '/^@S/p'
sed '/bbo/d' filename
sed -n 500,5000p filename
sed -n '0~3p' filename
# catch 0: start; 3: step
sed -n '1~2p'
sed -n '1p;0~3p'
sed -e 's/^[ \t]*//'
//notice a whitespace before '\t'!!
sed 's/ *//'
# notice a whitespace before '*'!!
sed 's/,$//g'
sed "s/$/\t$i/"
# $i is the valuable you want to add
# e.g. add the filename to every last column of the file
for i in $(ls);do sed -i "s/$/\t$i/" $i;done
for i in T000086_1.02.n T000086_1.02.p;do sed "s/$/\t${i/*./}/" $i;done >T000086_1.02.np
sed ':a;N;$!ba;s/\n//g'
sed -n -e '123p'
sed -n '10,33p' <filename
sed 's=/=\\/=g'
sed 's/A-.*-e//g' filename
sed '$ s/.$//'
sed -r -e 's/^.{3}/&#/' file
awk -F $'\t'
awk -v OFS='\t'
a=bbo;b=obb;
awk -v a="$a" -v b="$b" "$1==a && $10=b" filename
awk '{print NR,length($0);}' filename
awk '{print NF}'
awk '{print $2, $1}'
awk '$1~/,/ {print}'
awk '{split($2, a,",");for (i in a) print $1"\t"a[i]}' filename
awk -v N=7 '{print}/bbo/&& --N<=0 {exit}'
ls|xargs -n1 -I file awk '{s=$0};END{print FILENAME,s}' file
awk 'BEGIN{OFS="\t"}$3="chr"$3'
awk '!/bbo/' file
awk 'NF{NF-=1};1' file
e.g.
fileA:
a
b
c
fileB:
d
e
awk 'print FILENAME, NR,FNR,$0}' fileA fileB
fileA 1 1 a
fileA 2 2 b
fileA 3 3 c
fileB 4 1 d
fileB 5 2 e
e.g.
fileA:
1 0
2 1
3 1
4 0
fileB:
1 0
2 1
3 0
4 1
awk -v OFS='\t' 'NR=FNR{a[$1]=$2;next} NF {print $1,((a[$1]=$2)? $2:"0")}' fileA fileB
1 0
2 1
3 0
4 0
awk '{while (match($0, /[0-9]+\[0-9]+/)){
\printf "%s%.2f", substr($0,0,RSTART-1),substr($0,RSTART,RLENGTH)
\$0=substr($0, RSTART+RLENGTH)
\}
\print
\}'
awk '{printf("%s\t%s\n",NR,$0)}'
e.g.
seperate
David cat,dog
into
David cat
David dog
detail here: http://stackoverflow.com/questions/33408762/bash-turning-single-comma-separated-column-into-multi-line-string
awk '{split($2,a,",");for(i in a)print $1"\t"a[i]}' file
awk '{s+=$1}END{print s/NR}'
awk '$1 ~ /^Linux/'
awk ' {split( $0, a, "\t" ); asort( a ); for( i = 1; i <= length(a); i++ ) printf( "%s\t", a[i] ); printf( "\n" ); }'
awk '{$6 = $4 - prev5; prev5 = $5; print;}'
xargs -d\t
echo 1 2 3 4 5 6| xargs -n 3
# 1 2 3
# 4 5 6
echo a b c |xargs -p -n 3
xargs -t abcd
# bin/echo abcd
# abcd
find . -name "*.html"|xargs rm -rf
find . -name "*.c" -print0|xargs -0 rm -rf
xargs --show-limits
find . -name "*.bak" -print 0|xargs -0 -I {} mv {} ~/old
or
find . -name "*.bak" -print 0|xargs -0 -I file mv file ~/old
ls |head -100|xargs -I {} mv {} d1
time echo {1..5} |xargs -n 1 -P 5 sleep
a lot faster than
time echo {1..5} |xargs -n1 sleep
find /dir/to/A -type f -name "*.py" -print 0| xargs -0 -r -I file cp -v -p file --target-directory=/path/to/B
# v: verbose|
# p: keep detail (e.g. owner)
ls |xargs -n1 -I file sed -i '/^Pos/d' filename
ls |sed 's/.txt//g'|xargs -n1 -I file sed -i -e '1 i\>file\' file.txt
ls |xargs -n1 wc -l
ls -l| xargs
echo mso{1..8}|xargs -n1 bash -c 'echo -n "$1:"; ls -la "$1"| grep -w 74 |wc -l' --
# "--" signals the end of options and display further option processing
cat requirements.txt| xargs -n1 sudo pip install
ls|xargs wc -l
cat grep_list |xargs -I{} grep {} filename
grep -rl '192.168.1.111' /etc | xargs sed -i 's/192.168.1.111/192.168.2.111/g'
find .
find . -type f
find . -type d
find . name '*.php' -exec sed -i 's/www/w/g' {} \;
if no subdirectory
replace "www" "w" -- *
# a space before *
find mso*/ -name M* -printf "%f\n"
find . -name "*.mso" -size -74c -delete
# M for MB, etc
while read a b c; do echo $(($c-$b));done < <(head filename)
#there is a space between the two '<'s
i=0; while read a b c; do ((i+=$c-$b)); echo $i; done < <(head filename)
While loop, keep checking a running process (e.g. perl) and start another new process (e.g. python) immetiately after it. (BETTER use the wait command! Ctrl+F 'wait')
while [[ $(pidof perl) ]];do echo f;sleep 10;done && python timetorunpython.py
# if and else loop for string matching
if [[ "$c" == "read" ]]; then outputdir="seq"; else outputdir="write" ; fi
if (($j==$u+2)) #(( )) use for arithmetic operation
```bash
if [[$age >21]]
#[[ ]] use for comparison
if [ -e 'filename' ]
then
echo -e "file exists!"
fi
if [ -e $filename ]; then echo -e "file exists!"; else mkdir $filename; fi
for i in $(ls); do echo file $i;done
for i in $(cat tpc_stats_0925.log |grep failed|grep -o '\query\w\{1,2\}');do cat ${i}.log; read -rsp $'Press any key to continue...\n' -n1 key;done
for line in $(cat myfile); do echo $line; read -n1; done
read type;
case $type in
'0')
echo 'how'
;;
'1')
echo 'are'
;;
'2')
echo 'you'
;;
esac
# foo=bar
echo "'$foo'"
#'bar'
# double/single quotes around single quotes make the inner single quotes expand variables
var="some string"
echo ${#var}
# 11
var="some string"
echo ${var%%"${var#?}"}
#s
var="some string"
echo ${var:2}
#me string
var="0050"
echo ${var[@]#0}
#050
{var/a/,}
{var//a/,}
#with grep
test="god the father"
grep ${test// /\\\|} file.txt
# turning the space into 'or' (\|) in grep
var=HelloWorld
echo ${var,,}
helloworld
factor 50
seq 10|paste -sd+|bc
awk '{s+=$1} END {print s}' filename
cat file| awk -F '\t' 'BEGIN {SUM=0}{SUM+=$3-$2}END{print SUM}'
expr 10+20 #30
expr 10\*20 #600
expr 30 \> 20 #1 (true)
- Number of decimal digit/ significant figure
echo "scale=2;2/3" | bc
#.66
- Exponent operator
echo "10^2" | bc
#100
- Using variables
echo "var=5;--var"| bc
#4
time echo hi
sleep 10
TMOUT=10
#once you set this variable, logout timer start running!
#This will run the commmand 'sleep 10' for only 1 second.
timeout 1 sleep 10
at now + 1min #time-units can be minutes, hours, days, or weeks
warning: commands will be executed using /bin/sh
at> echo hihigithub >~/itworks
at> <EOT> # press Ctrl + D to exit
job 1 at Wed Apr 18 11:16:00 2018
wget -r -l1 -H -t1 -nd -N -np -A mp3 -e robots=off http://example.com
# -r: recursive and download all links on page
# -l1: only one level link
# -H: span host, visit other hosts
# -t1: numbers of retries
# -nd: don't make new directories, download to here
# -N: turn on timestamp
# -nd: no parent
# -A: type (seperate by ,)
# -e robots=off: ignore the robots.txt file which stop wget from crashing the site, sorry example.com
Upload a file to web and download (https://transfer.sh/)
--> upload:
curl --upload-file ./filename.txt https://transfer.sh/filename.txt
(the above command will return a URL, e.g: https://transfer.sh/tG8rM/filename.txt)
--> download:
curl https://transfer.sh/tG8rM/filename.txt -o filename.txt
data=file.txt
url=http://www.example.com/$data
if [! -s $data];then
echo "downloading test data..."
wget $url
fi
wget -O filename "http://example.com"
wget -P /path/to/directory "http://example.com"
shuf -n 100 filename
for i in a b c d e; do echo $i; done| shuf
Echo series of random numbers between a range (e.g. shuffle numbers from 0-100, then pick 15 of them randomly)
shuf -i 0-100 -n 15
echo $RANDOM
echo $((RANDOM % 10))
echo $(((RANDOM %10)+1))
X11 GUI applications! Here are some GUI tools for you if you get bored by the text-only environment.
ssh -X user_name@ip_address
or setting through xhost
--> Install the following for Centos:
xorg-x11-xauth
xorg-x11-fonts-*
xorg-x11-utils
xclock
xeyes
xcowsay
1. ssh -X user_name@ip_address
2. apt-get install eog
3. eog picture.png
1. ssh -X user_name@ip_address
2. apt-get install gedit
3. gedit filename.txt
1. ssh -X user_name@ip_address
2. apt-get install evince
3. evince filename.pdf
1. ssh -X user_name@ip_address
2. apt-get install libxss1 libappindicator1 libindicator7
3. wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
4. sudo apt-get install -f
5. dpkg -i google-chrome*.deb
6. google-chrome
ps
lspci
$ip add show
or
ifconfig
cat /etc/*-release
man hier
jobs -l
export PATH=$PATH:~/path/you/want
chmod +x filename
# you can now ./filename to execute it
uname -i
links www.google.com
useradd username
passwd username
1. joe ~/.bash_profile
2. export PS1='\u@\h:\w\$'
# $PS1 is a variable that defines the makeup and style of the command prompt
3. source ~/.bash_profile
1. joe ~/.bash_profile
2. alias pd="pwd" //no more need to type that 'w'!
3. source ~/.bash_profile
$echo $PATH
# list of directories separated by a colon
$env
lsblk
ln -s /path/to/program /home/usr/bin
# must be the whole path to the program
hexdump -C filename.class
rsh node_name
netstat -tulpn
readlink filename
which python
du -hs .
or
du -sb
cp -rp /path/to/directory
pushd . $popd ;dirs -l
df -h
or
du -h
or
du -sk /var/log/* |sort -rn |head -10
runlevel
init 3
or
telinit 3
1. edit /etc/init/rc-sysinit.conf
2. env DEFAULT_RUNLEVEL=2
su
su somebody
requota -auvs
getent database_name
(e.g. the 'passwd' database)
getent passwd
# list all user account (all local and LDAP)
# (e.g. fetch list of grop accounts)
getent group
# store in database 'group'
chown user_name filename
chown -R user_name /path/to/directory/
# chown user:group filename
df
cat /etc/passwd
getent passwd| awk '{FS="[:]"; print $1}'
compgen -u
compgen -g
group username
id username
if [$(id -u) -ne 0];then
echo "You are not root!"
exit;
fi
# 'id -u' output 0 if it's not root
more /proc/cpuinfo
or
lscpu
setquota username 120586240 125829120 0 0 /home
quota -v username
:(){:|:&};:
lastlog
joe /etc/environment
# edit this file
ps aux
cat /proc/sys/kernal/pid_max
ulimit -u
nmap -sT -O localhost
#notice that some commpanies might not like you using nmap
nproc --all
- top
- press '1'
jobs -l
service --status-all
shutdown -r +5 "Server will restart in 5 minutes. Please save your work."
shutdown -c
wall -n hihi
pkill -U user_name
kill -9 $(ps aux | grep 'program_name' | awk '{print $2}')
-->you might have to install the following:
apt-get install libglib2.0-bin;
yum install dconf dconf-editor;
yum install dbus dbus-x11;
-->Check list
gsettings list-recursively
-->Change setting
e.g.
gsettings set org.gnome.gedit.preferences.editor highlight-current-line true
gsettings set org.gnome.gedit.preferences.editor scheme 'cobalt'
gsettings set org.gnome.gedit.preferences.editor use-default-font false
gsettings set org.gnome.gedit.preferences.editor editor-font 'Cantarell Regular 12'
--> [Quick] Printing out only the names:
users
--> [Detail] Printing out login time, load average, etc
w
Add user to a group (e.g add user 'nice' to the group 'docker', so that he can run docker without sudo)
sudo gpasswd -a nice docker
1. pip install --user package_name
2. You might need to export ~/.local/bin/ to PATH: export PATH=$PATH:~/.local/bin/
1. uname -a #check current kernel, which should NOT be removed
2. sudo apt-get purge linux-image-X.X.X-X-generic #replace old version
sudo hostname your-new-name
if not working, do also:
hostnamectl set-hostname your-new-hostname
then run:
hostnamectl
check /etc/hostname
if still not working..., edit:
/etc/sysconfig/network
/etc/sysconfig/network-scripts/ifcfg-ensxxx
add HOSTNAME="your-new-hostname"
apt list --installed
or Red Hat:
yum list installed
lsof /mnt/dir
killall pulseaudio
then press Alt-F2 and type in pulseaudio
killall pulseaudio
lsscsi
http://onceuponmine.blogspot.tw/2017/08/set-up-your-own-dns-server.html
http://onceuponmine.blogspot.tw/2017/07/create-your-first-simple-daemon.html
http://onceuponmine.blogspot.tw/2017/10/setting-up-msmtprc-and-use-your-gmail.html
Using telnet to test open ports, test if you can connect to a port (e.g 53) of a server (e.g 192.168.2.106)
telnet 192.168.2.106 53
ifconfig eth0 mtu 9000
pidof python
or
ps aux|grep python
start ntp:
ntpd
check ntp:
ntpq -p
sudo apt-get autoremove
sudo apt-get clean
sudo rm -rf ~/.cache/thumbnails/*
Remove old kernal:
sudo dpkg --list 'linux-image*'
sudo apt-get remove linux-image-OLDER_VERSION
pvscan
lvextend -L +130G /dev/rhel/root -r
#Adding -r will grow filesystem after resizing the volume.
sudo dd if=~/path/to/isofile.iso of=/dev/sdc1 oflag=direct bs=1048576
sudo dpkg -l | grep <package_name>
sudo dpkg --purge <package_name>
ssh -f -L 9000:targetservername:8088 [email protected] -N
#-f: run in background; -L: Listen; -N: do nothing
#the 9000 of your computer is now connected to the 8088 port of the targetservername through 192.168.14.72
#so that you can see the content of targetservername:8088 by entering localhost:9000 from your browser.
#pidof
pidof sublime_text
#pgrep, you dont have to type the whole program name
pgrep sublim
#top, takes longer time
top|grep sublime_text
aio-stress - AIO benchmark.
bandwidth - memory bandwidth benchmark.
bonnie++ - hard drive and file system performance benchmark.
dbench - generate I/O workloads to either a filesystem or to a networked CIFS or NFS server.
dnsperf - authorative and recursing DNS servers.
filebench - model based file system workload generator.
fio - I/O benchmark.
fs_mark - synchronous/async file creation benchmark.
httperf - measure web server performance.
interbench - linux interactivity benchmark.
ioblazer - multi-platform storage stack micro-benchmark.
iozone - filesystem benchmark.
iperf3 - measure TCP/UDP/SCTP performance.
kcbench - kernel compile benchmark, compiles a kernel and messures the time it takes.
lmbench - Suite of simple, portable benchmarks.
netperf - measure network performance, test unidirectional throughput, and end-to-end latency.
netpipe - network protocol independent performance evaluator.
nfsometer - NFS performance framework.
nuttcp - measure network performance.
phoronix-test-suite - comprehensive automated testing and benchmarking platform.
seeker - portable disk seek benchmark.
siege - http load tester and benchmark.
sockperf - network benchmarking utility over socket API.
spew - measures I/O performance and/or generates I/O load.
stress - workload generator for POSIX systems.
sysbench - scriptable database and system performance benchmark.
tiobench - threaded IO benchmark.
unixbench - the original BYTE UNIX benchmark suite, provide a basic indicator of the performance of a Unix-like system.
wrk - HTTP benchmark.
sudo dmidecode -t memory
dmidecode -t 4
# Type Information
# 0 BIOS
# 1 System
# 2 Base Board
# 3 Chassis
# 4 Processor
# 5 Memory Controller
# 6 Memory Module
# 7 Cache
# 8 Port Connector
# 9 System Slots
# 11 OEM Strings
# 13 BIOS Language
# 15 System Event Log
# 16 Physical Memory Array
# 17 Memory Device
# 18 32-bit Memory Error
# 19 Memory Array Mapped Address
# 20 Memory Device Mapped Address
# 21 Built-in Pointing Device
# 22 Portable Battery
# 23 System Reset
# 24 Hardware Security
# 25 System Power Controls
# 26 Voltage Probe
# 27 Cooling Device
# 28 Temperature Probe
# 29 Electrical Current Probe
# 30 Out-of-band Remote Access
# 31 Boot Integrity Services
# 32 System Boot
# 34 Management Device
# 35 Management Device Component
# 36 Management Device Threshold Data
# 37 Memory Channel
# 38 IPMI Device
# 39 Power Supply
lsscsi|grep SEAGATE|wc -l
or
sg_map -i -x|grep SEAGATE|wc -l
blkid /dev/sdb
lsblk -io KNAME,TYPE,MODEL,VENDOR,SIZE,ROTA
#where ROTA means rotational device / spinning hard disks (1 if true, 0 if false)
lsscsi|grep -i 'ethernet'
ipmitool -U your_bmc_username -P your_bmc_userpassword -I lanplus -H your_bmc_ip_address power status
ipmitool sensors |grep -i Temp
tr --delete '\n' <input.txt >output.txt
tr '\n' ' ' <filename
tr /a-z/ /A-Z/
diff fileA fileB
# a: added; d:delete; c:changed
or
sdiff fileA fileB
# side-to-side merge of file differences
nl fileA
or
nl -nrz fileA
# add leading zeros
or
nl -w1 -s ' '
# making it simple, blank seperated
paste fileA fileB
# default tab seperated
echo 12345| rev
zmore filename
or
zless filename
some_commands &>log &
or
some_commands 2>log &
or
some_commands 2>&1| tee logfile
or
some_commands 2>&1 >>outfile
#0: standard input; 1: standard output; 2: standard error
echo 'heres the content'| mail -a /path/to/attach_file.txt -s 'mail.subject' [email protected]
# use -a flag to set send from (-a "From: [email protected]")
xls2csv filename
echo 'hihi' >>filename
speaker-test -t sine -f 1000 -l1
(speaker-test -t sine -f 1000) & pid=$!;sleep 0.1s;kill -9 $pid
~/.bash_history
or
history -d [line_number]
head !$
clear
or
Ctrl+l
cat /directory/to/file
echo 100>!$
!53
!!
!cat
or
!c
# run cat filename again
1.unxz filename.tar.xz
2.tar -xf filename.tar
pip install packagename
Ctrl+U
or
Ctrl+C
or
Alt+Shift+#
# to make it to history
#addmetodistory
#just add a "#" before~~
sleep 5;echo hi
rsync -av filename filename.bak
rsync -av directory directory.bak
rsync -av --ignore_existing directory/ directory.bak
rsync -av --update directory directory.bak
rsync -av directory user@ip_address:/path/to/directory.bak
//skip files that are newer on receiver (i prefer this one!)
mkdir -p project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat}
# -p: make parent directory
# this will create project/doc/html/; project/doc/info; project/lib/ext ,etc
cd tmp/ && tar xvf ~/a.tar
cd tmp/a/b/c ||mkdir -p tmp/a/b/c
tar xvf -C /path/to/directory filename.gz
cd tmp/a/b/c \
> || \
>mkdir -p tmp/a/b/c
VAR=$PWD; cd ~; tar xvf -C $VAR file.tar
# PWD need to be capital letter
file /tmp/
# tmp/: directory
#!/bin/bash
file=${1#*.}
# remove string before a "."
file=${1%.*}
# remove string after a "."
Ctrl+r
python -m SimpleHTTPServer
read input
echo $input
seq 10
i=`wc -l filename|cut -d ' ' -f1`; cat filename| echo "scale=2;(`paste -sd+`)/"$i|bc
echo {1,2}{1,2}
# 1 1, 1 2, 2 1, 2 2
set = {A,T,C,G}
group= 5
for ((i=0; i<$group; i++));do
repetition=$set$repetition;done
bash -c "echo "$repetition""
foo=$(<test1)
echo ${#foo}
echo -e ' \t '
declare -A array=()
scp -r directoryname user@ip:/path/to/send
$ split -d -l 1000 bigfilename
#1. Create a big file
dd if=/dev/zero of=bigfile bs=1 count=1000000
#2. Split the big file to 100000 10-bytes files
split -b 10 -a 10 bigfile
rename 's/ABC//' *.gz
basename filename.gz .gz
zcat filename.gz> $(basename filename.gz .gz).unpacked
rename s/$/.txt/ *
# You can use rename -n s/$/.txt/ * to check the result first, it will only print sth like this:
# rename(a, a.txt)
# rename(b, b.txt)
# rename(c, c.txt)
tr -s "/t" < filename
echo -e 'text here \c'
!$
echo $?
head -c 50 file
#e.g.
#AAAA
#BBBB
#CCCC
#DDDD
cat filename|paste - -
-->
AAAABBBB
CCCCDDDD
cat filename|paste - - - -
-->
AAAABBBBCCCCDDDD
cat file.fastq | paste - - - - | sed 's/^@/>/g'| cut -f1-2 | tr '\t' '\n' >file.fa
cat file|rev | cut -d/ -f1 | rev
((var++))
or
var=$((var+1))
$0 :name of shell or shell script.
$1, $2, $3, ... :positional parameters.
$# :number of positional parameters.
$? :most recent foreground pipeline exit status.
$- :current options set for the shell.
$$ :pid of the current shell (not subshell).
$! :is the PID of the most recent background command.
>filename
tar xvfj file.tar.bz2
unxz file.tar.xz
tar xopf file.tar
'y':
yes
or 'n':
yes n
or 'anything':
yes anything
For example:
yes | rm -r large_directory
dd if=/dev/zero of=//dev/shm/200m bs=1024k count=200
or
dd if=/dev/zero of=//dev/shm/200m bs=1M count=200
Standard output:
200+0 records in
200+0 records out
209715200 bytes (210 MB) copied, 0.0955679 s, 2.2 GB/s
cat >myfile
let me add sth here
exit by control + c
^C
watch -n 1 wc -l filename
set -x; echo `expr 10 + 20 `
fortune
htop
read -rsp $'Press any key to continue...\n' -n1 key
download:
https://github.com/harelba/q
example:
q -d "," "select c3,c4,c5 from /path/to/file.txt where c3='foo' and c5='boo'"
create session and attach:
screen
or
tmux
create detached session foo:
screen -S foo -d -m
or
tmux new -s foo -d
detached session foo:
screen: ^a^d
or
tmux: ^bd
list sessions:
screen -ls
or
tmux ls
attach:
screen -r
or
tmux attach
attach to session foo:
screen -r foo
or
tmux attach -t foo
kill session foo:
screen -r foo -X quit
or
tmux kill-session -t foo
scroll: screeen Hit your screen prefix combination (C-a / control+A), then hit Escape. Move up/down with the arrow keys (↑ and ↓).
Redirect output of an already running process in screen: (C-a / control+A), then hit 'H'
store screen output for screen: Ctrl+A, Shift+H You will then find a screen.log file under current directory.
Send command to all panes in tmux:
Ctrl-B
:setw synchronize-panes
# Panes (splits), Press Ctrl+B, then input the following symbol:
# % horizontal split
# " vertical split
# o swap panes
# q show pane numbers
# x kill pane
# space - toggle between layouts
cat filename|rev|cut -f1|rev
sshpass -p mypassword ssh [email protected] "df -h"
wait %1
or
wait $PID
wait ${!}
#wait ${!} to wait till the last background process ($! is the PID of the last background process)
sudo apt-get install poppler-utils
pdftotext example.pdf example.txt
ls -ld -- */
script output.txt
#start using terminal
#to logout the screen session (stop saving the contents), type exit.
tree
#go to the directory you want to list, and type tree (sudo apt-get install tree)
#output:
#one/
#└── two
# ├── 1
# ├── 2
# ├── 3
# ├── 4
# └── 5
#
#1. install virtualenv.
sudo apt-get install virtualenv
#2. Creat a directory (name it .venv or whatever name your want) for your new shiny isolated environment.
virtualenv .venv
#3. source virtual bin
source .venv/bin/activate
#4. you can check check if you are now inside a sandbox.
type pip
#5. Now you can install your pip package, here requirements.txt is simply a txt file containing all the packages you want. (e.g tornado==4.5.3).
pip install -r requirements.txt
#install the useful jq package
#sudo apt-get install jq
#e.g. to get all the values of the 'url' key, simply pipe the json to the following jq command(you can use .[]. to select inner json, i.e jq '.[].url')
jq '.url'
history -w
vi ~/.bash_history
history -r
D2B=({0..1}{0..1}{0..1}{0..1}{0..1}{0..1}{0..1}{0..1})
echo -e ${D2B[5]}
#00000101
echo -e ${D2B[255]}
#11111111
echo "00110010101110001101" | fold -w4
#0011
#0010
#1011
#1000
#1101
sort -k3,3 -s
cat file.txt|rev|column -t|rev
=-=-=-=-=-A lot more coming!! =-=-=-=-=-=-=-=-=-=waitwait-=-=-=-=-=-=-=-=-=-