onceupon/Bash-Oneliner

Ctrl + a : move to the beginning of line.
Ctrl + d : if you've type something, Ctrl + d deletes the character under the cursor, else, it escapes the current shell.
Ctrl + e : move to the end of line.
Ctrl + k : delete all text from the cursor to the end of line.
Ctrl + l : equivalent to clear.
Ctrl + n : same as Down arrow.
Ctrl + p : same as Up arrow.
Ctrl + q : to resume output to terminal after Ctrl + s.
Ctrl + r : begins a backward search through command history.(keep pressing Ctrl + r to move backward)
Ctrl + s : to stop output to terminal.
Ctrl + t : transpose the character before the cursor with the one under the cursor, press Esc + t to transposes the two words before the cursor.
Ctrl + u : cut the line before the cursor; then Ctrl + y paste it
Ctrl + w : cut the word before the cursor; then Ctrl + y paste it
Ctrl + x + backspace : delete all text from the beginning of line to the cursor.
Ctrl + x + Ctrl + e : launch editor defined by $EDITOR to input your command. Useful for multi-line commands.
Ctrl + z : stop current running process and keep it in background. You can use `fg` to continue the process in the foreground, or `bg` to continue the process in the background.
Ctrl + _ : undo typing.

Esc + u
# converts text from cursor to the end of the word to uppercase.
Esc + l
# converts text from cursor to the end of the word to lowercase.
Esc + c
# converts letter under the cursor to uppercase, rest of the word to lowercase.

!53

!!
# run the previous command using sudo
sudo !!

# last command: echo 'aaa'
^aaa^bbb

#echo 'bbb'
#bbb

# Notice that only the first aaa will be replaced, if you want to replace all 'aaa', use ':&' to repeat it:
^aaa^bbb^:&
# or
!!:gs/aaa/bbb/

!cat
# or
!c
# run cat filename again

# '*' serves as a "wild card" for filename expansion.
/etc/pa*wd    #/etc/passwd

# '?' serves as a single-character "wild card" for filename expansion.
/b?n/?at      #/bin/cat

# '[]' serves to match the character from a range.
ls -l [a-z]*   #list all files with alphabet in its filename.

# '{}' can be used to match filenames with more than one patterns
ls *.{sh,py}   #list all .sh and .py files

$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.
$_   :last argument of the previously executed command, or the path of the bash script.

$DESKTOP_SESSION     current display manager
$EDITOR   preferred text editor.
$LANG   current language.
$PATH   list of directories to search for executable files (i.e. ready-to-run programs)
$PWD    current directory
$SHELL  current shell
$USER   current username
$HOSTNAME   current hostname

set -o vi
# change bash shell to vi mode
# then hit the Esc key to change to vi edit mode (when `set -o vi` is set)
k
# in vi edit mode - previous command
j
# in vi edit mode - next command
0
# in vi edit mode - beginning of the command
R
# in vi edit mode - replace current characters of command
2w
# in vi edit mode - next to 2nd word
b
# in vi edit mode - previous word
i
# in vi edit mode - go to insert mode
v
# in vi edit mode - edit current command in vi
man 3 readline
# man page for complete readline mapping

# foo=bar
echo $foo
# bar
echo "$foo"
# bar
# single quotes cause variables to not be expanded
echo '$foo'
# $foo
# single quotes within double quotes will not cancel expansion and will be part of the output
echo "'$foo'"
# 'bar'
# doubled single quotes act as if there are no quotes at all
echo ''$foo''
# bar

var="some string"
echo ${#var}
# 11

var=string
echo "${var:0:1}"
#s

# or
echo ${var%%"${var#?}"}

var="some string"
echo ${var:2}
#me string

var="0050"
echo ${var[@]#0}
#050

{var/a/,}

{var//a/,}

export NAME="Alice"
envsubst < template.txt > output.txt
# template.txt:       Hello ${NAME}, your order is shipped.
# output.txt:         Hello Alice, your order is shipped.
# or
export USER="Bob" && echo 'Hi $USER, welcome!' | envsubst
# Hi Bob, welcome!

# with grep
test="stringA stringB stringC"
grep ${test// /\\\|} file.txt
# turning the space into 'or' (\|) in grep

var=HelloWorld
echo ${var,,}
helloworld

cmd="bar=foo"
eval "$cmd"
echo "$bar" # foo

# https://github.com/asciinema/asciinema
asciinema rec demo.cast

echo $(( 10 + 5 ))  #15
x=1
echo $(( x++ )) #1 , notice that it is still 1, since it's post-increment
echo $(( x++ )) #2
echo $(( ++x )) #4 , notice that it is not 3 since it's pre-increment
echo $(( x-- )) #4
echo $(( x-- )) #3
echo $(( --x )) #1
x=2
y=3
echo $(( x ** y )) #8

factor 50
# 50: 2 5 5

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

grep = grep -G # Basic Regular Expression (BRE)
fgrep = grep -F # fixed text, ignoring meta-characters
egrep = grep -E # Extended Regular Expression (ERE)
rgrep = grep -r # recursive
grep -P # Perl Compatible Regular Expressions (PCRE)

grep -c "^$"

grep -o '[0-9]*'
# or
grep -oP '\d*'

grep '[0-9]\{3\}'

# or
grep -E '[0-9]{3}'

# or
grep -P '\d{3}'

grep -Eo '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'

# or
grep -Po '\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}'

grep -w 'target'

# or using RE
grep '\btarget\b'

# return also 3 lines after match
grep -A 3 'bbo'

# return also 3 lines before match
grep -B 3 'bbo'

# return also 3 lines before and after match
grep -C 3 'bbo'

grep -o 'S.*'

grep -o -P '(?<=w1).*(?=w2)'

grep -v bbo filename

grep -v '^#' file.txt

grep "$myvar" filename
# remember to quote the variable!

grep -m 1 bbo filename

grep -c bbo filename

grep -o bbo filename |wc -l

grep -i "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

grep -rl bbo /path/to/directory

grep 'A\|B\|C\|D'

grep 'A.*B'

grep 'A.B'

grep 'colou\?r'

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

grep -d skip 'bbo' /path/to/files/*

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 >$i to the first line (to make a bioinformatics FASTA file)
sed "1i >$i"
# notice the double quotes! in other examples, you can use a single quote, but here, no way!
# '1i' means insert to first line

# Use backslash for end-of-line $ pattern, and double quotes for expressing the variable
sed -e "\$s/\$/\n+--$3-----+/"

sed '/^\s*$/d'

# or

sed '/^$/d'

sed '$d'

sed -i '$ s/.$//' filename

sed -i '1s/^/[/' filename

sed -e '1isomething' -e '3isomething'

sed '$s/$/]/' filename

sed '$a\'

sed -e 's/^/bbo/' filename

sed -e 's/$/\}\]/' filename

sed 's/.\{4\}/&\n/g'

sed '/hello*/a world' filename
# hello
# world

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

# To 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}/&#/' filename

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}' filename

awk 'BEGIN{OFS="\t"}$3="chr"$3'

awk '!/bbo/' filename

awk 'NF{NF-=1};1' filename

# For example there are two files:
# 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

# For example there are two files:
# 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)}'

# For example, separate the following content:
# David    cat,dog
# into
# David    cat
# David    dog

awk '{split($2,a,",");for(i in a)print $1"\t"a[i]}' filename

# Detail here:　http://stackoverflow.com/questions/33408762/bash-turning-single-comma-separated-column-into-multi-line-string

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

ls|xargs -L1 -p head

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

# when using a backtick
rm `find . -name "*.html"`

find . -name "*.c" -print0|xargs -0 rm -rf

xargs --show-limits
# Output from my Ubuntu:
# Your environment variables take up 3653 bytes
# POSIX upper limit on argument length (this system): 2091451
# POSIX smallest allowable upper limit on argument length (all systems): 4096
# Maximum length of command we could actually use: 2087798
# Size of command buffer we are actually using: 131072
# Maximum parallelism (--max-procs must be no greater): 2147483647

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

ls|xargs wc -l

cat grep_list |xargs -I{} grep {} filename

grep -rl '192.0.2.1' /etc | xargs sed -i 's/192.0.2.1/192.0.2.2/g'

find .

find . -type f

find . -type d

find . -name '*.php' -exec sed -i 's/www/w/g' {} \;

# if there are no subdirectory
replace "www" "w" -- *
# a space before *

find mso*/ -name M* -printf "%f\n"

find / -type f -size +4G

find . -name "*.mso" -size -74c -delete

# M for MB, etc

find . -type f -empty
# to further delete all the empty files
find . -type f -empty -delete

find . -type f | wc -l

# if and else loop for string matching
if [[ "$c" == "read" ]]; then outputdir="seq"; else outputdir="write" ; fi

# Test if myfile contains the string 'test':
if grep -q hello myfile; then echo -e "file contains the string!" ; fi

# Test if mydir is a directory, change to it and do other stuff:
if cd mydir; then
  echo 'some content' >myfile
else
  echo >&2 "Fatal error. This script requires mydir."
fi

# Check if a variable is null
if [ -z "$var" ]; then echo "NULL"; else echo "Not NULL"; fi
# or 
[ -z "$var" ] && echo "NULL"

# Using test command (same as []), to test if the length of variable is nonzero
test -n "$myvariable" && echo myvariable is "$myvariable" || echo myvariable is not set

# Test if file exist
if [ -e 'filename' ]
then
  echo -e "file exists!"
fi

# Test if file exist but also including symbolic links:
if [ -e myfile ] || [ -L myfile ]
then
  echo -e "file exists!"
fi

# Test if the value of x is greater or equal than 5
if [ "$x" -ge 5 ]; then echo -e "greater or equal than 5!" ; fi

# Test if the value of x is greater or equal than 5, in bash/ksh/zsh:
if ((x >= 5)); then echo -e "greater or equal than 5!" ; fi

# Use (( )) for arithmetic operation
if ((j==u+2)); then echo -e "j==u+2!!" ; fi

# Use [[ ]] for comparison
if [[ $age -gt 21 ]]; then echo -e "forever 21!!" ; fi

# Echo the file name under the current directory
for i in $(ls); do echo file $i; done
# or
for i in *; do echo file $i; done

# Make directories listed in a file (e.g. myfile)
for dir in $(<myfile); do mkdir $dir; done

# Press any key to continue each loop
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

# Print a file line by line when a key is pressed,
oifs="$IFS"; IFS=$'\n'; for line in $(cat myfile); do ...; done
while read -r line; do ...; done <myfile

# If only one word a line, simply
for line in $(cat myfile); do echo $line; read -n1; done

# Loop through an array
for i in "${arrayName[@]}"; do echo $i; done

# Column subtraction of a file (e.g. a 3 columns file)
while read a b c; do echo $(($c-$b)); done < <(head filename)
#there is a space between the two '<'s

# Sum up column subtraction
i=0; while read a b c; do ((i+=$c-$b)); echo $i; done < <(head filename)

# Keep checking a running process (e.g. perl) and start another new process (e.g. python) immediately after it. (BETTER use the wait command! Ctrl+F 'wait')
while [[ $(pidof perl) ]]; do echo f; sleep 10; done && python timetorunpython.py

read type;
case $type in
  '0')
    echo 'how'
    ;;
  '1')
    echo 'are'
    ;;
  '2')
    echo 'you'
    ;;
esac

time echo hi

sleep 10

date +%F
# 2020-07-19

# or
date +'%d-%b-%Y-%H:%M:%S'
# 10-Apr-2020-21:54:40

# Returns the current time with nanoseconds.
date +"%T.%N"
# 11:42:18.664217000  

# Get the seconds since epoch (Jan 1 1970) for a given date (e.g Mar 16 2021)
date -d "Mar 16 2021" +%s
# 1615852800
# or
date -d "Tue Mar 16 00:00:00 UTC 2021"  +%s
# 1615852800  

# Convert the number of seconds since epoch back to date
date --date @1615852800
# Tue Mar 16 00:00:00 UTC 2021

# print current date first (for the following example)
date +"%F %H:%M:%S"
# 2023-03-11 16:17:09

# print the time that is 1 day ago
date -d"1 day ago" +"%F %H:%M:%S"
# 2023-03-10 16:17:09

# print the time that is 7 days ago
date -d"7 days ago" +"%F %H:%M:%S"
# 2023-03-04 16:17:09

# print the time that is a week ago
date -d"1 week ago" +"%F %H:%M:%S"
# 2023-03-04 16:17:09

# add 1 day to date
date -d"-1 day ago" +"%F %H:%M:%S"
# 2023-03-12 16:17:09

sleep $[ ( $RANDOM % 5 ) + 1 ]

TMOUT=10
#once you set this variable, logout timer start running!

# This will run the command '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

curl https://raw.githubusercontent.com/onceupon/Bash-Oneliner/master/README.md | pandoc -f markdown -t man | man -l -

# or w3m (a text based web browser and pager)
curl https://raw.githubusercontent.com/onceupon/Bash-Oneliner/master/README.md | pandoc | w3m -T text/html

# or using emacs (in emac text editor)
emacs --eval '(org-mode)' --insert <(curl https://raw.githubusercontent.com/onceupon/Bash-Oneliner/master/README.md | pandoc -t org)

# or using emacs (on terminal, exit using Ctrl + x then Ctrl + c)
emacs -nw --eval '(org-mode)' --insert <(curl https://raw.githubusercontent.com/onceupon/Bash-Oneliner/master/README.md | pandoc -t org)

wget -r -l1 -H -t1 -nd -N -np -A mp3 -e robots=off http://example.net

# -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 (separate by ,)
# -e robots=off: ignore the robots.txt file which stop wget from crashing the site, sorry example.net

#  Upload a file (e.g. filename.txt):
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

# Next you can download it by:
curl https://transfer.sh/tG8rM/filename.txt -o filename.txt

data=file.txt
url=http://www.example.net/$data
if [ ! -s $data ];then
    echo "downloading test data..."
    wget $url
fi

wget -O filename "http://example.net"

wget -P /path/to/directory "http://example.net"

curl -L example.net

sudo apt install pwgen
pwgen 13 5
#sahcahS9dah4a xieXaiJaey7xa UuMeo0ma7eic9 Ahpah9see3zai acerae7Huigh7

shuf -n 100 filename

for i in a b c d e; do echo $i; done | shuf

shuf -i 0-100 -n 15

echo $RANDOM

echo $((RANDOM % 10))

echo $(((RANDOM %10)+1))

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. sudo apt install mpv
3. mpv myvideo.mp4

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.example.net/linux/direct/google-chrome-stable_current_amd64.deb
4. sudo apt-get install -f
5. dpkg -i google-chrome*.deb
6. google-chrome

# List yum history (e.g install, update)
sudo yum history
# Example output:
# Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
# ID     | Login user               | Date and time    | Action(s)      | Altered
# -------------------------------------------------------------------------------
#     11 |  ... <myuser>       | 2020-04-10 10:57 | Install        |    1 P<
#     10 |  ... <myuser>       | 2020-03-27 05:21 | Install        |    1 >P
#      9 |  ... <myuser>       | 2020-03-05 11:57 | I, U           |   56 *<
# ...

# Show more details of a yum history (e.g. history #11)
sudo yum history info 11

# Undo a yum history (e.g. history #11, this will uninstall some packages)
sudo yum history undo 11

# To audit a directory recursively for changes (e.g. myproject)
auditctl -w /path/to/myproject/ -p wa

# If you delete a file name "VIPfile", the deletion is recorded in /var/log/audit/audit.log
sudo grep VIPfile /var/log/audit/audit.log
#type=PATH msg=audit(1581417313.678:113): item=1 name="VIPfile" inode=300115 dev=ca:01 mode=0100664 ouid=1000 ogid=1000 rdev=00:00 nametype=DELETE cap_fp=0000000000000000 cap_fi=0000000000000000 cap_fe=0 cap_fver=0

sestatus
# SELinux status:                 enabled
# SELinuxfs mount:                /sys/fs/selinux
# SELinux root directory:         /etc/selinux
# Loaded policy name:             targeted
# Current mode:                   enforcing
# Mode from config file:          enforcing
# Policy MLS status:              enabled
# Policy deny_unknown status:     allowed
# Max kernel policy version:      31

ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub

ssh-copy-id <user_name>@<server_IP>
# then you need to enter the password
# and next time you won't need to enter password when ssh to that user

# before you need to use mykey.pem to ssh to remote user.
ssh-copy-id -i ~/.ssh/id_rsa.pub -o "IdentityFile ~/Downloads/mykey.pem" <user_name>@<server_IP>
# now you don't need to use key to ssh to that user.

# To bring your key with you when ssh to serverA, then ssh to serverB from serverA using the key.
ssh-agent
ssh-add /path/to/mykey.pem
ssh -A <username>@<IP_of_serverA>
# Next you can ssh to serverB
ssh <username>@<IP_of_serverB>

# add the following to ~/.ssh/config
Host myserver
  User myuser
  IdentityFile ~/path/to/mykey.pem

# Next, you could run "ssh myserver" instead of "ssh -i ~/path/to/mykey.pem myuser@myserver"

journalctl -u <service_name> -f

# A zombie is already dead, so you cannot kill it. You can eliminate the zombie by killing its parent.
# First, find PID of the zombie
ps aux| grep 'Z'
# Next find the PID of zombie's parent
pstree -p -s <zombie_PID>
# Then you can kill its parent and you will notice the zombie is gone.
sudo kill 9 <parent_PID>

free -c 10 -mhs 1
# print 10 times, at 1 second interval

# refresh every second
iostat -x -t 1

iftop -i enp175s0f0

uptime

if [ "$EUID" -ne 0 ]; then
        echo "Please run this as root"
        exit 1
fi

chsh -s /bin/sh bonnie
# /etc/shells: valid login shells

chroot /home/newroot /bin/bash

# To exit chroot
exit

stat filename.txt

ps aux

ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%mem | head

pstree

# or
ps aux --forest

cat /proc/sys/kernel/pid_max

dmesg

$ip add show

# or
ifconfig

runlevel

# or
who -r

init 5
# or
telinit 5

chkconfig --list
# update-rc.d equivalent to chkconfig in ubuntu

cat /etc/*-release

man hier

# e.g. check the status of cron service
systemctl status cron.service

# e.g. stop cron service
systemctl stop cron.service

jobs -l

# nice value is adjustable from -20 (most favorable) to +19
# the nicer the application, the lower the priority
# Default niceness: 10; default priority: 80

nice -10 ./test.sh

export PATH=$PATH:~/path/you/want

chmod +x filename
# you can now ./filename to execute it

uname -a

# Check system hardware-platform (x86-64)
uname -i

links www.example.net

useradd username
passwd username

1. vi ~/.bash_profile
2. export PS1='\u@\h:\w\$'
# $PS1 is a variable that defines the makeup and style of the command prompt
# You could use emojis and add timestamp to every prompt using the following value:
# export PS1="\t@🦁:\w\$ "
3. source ~/.bash_profile

1. vi ~/.bash_profile
2. alias pd="pwd" //no more need to type that 'w'!
3. source ~/.bash_profile

alias -p

unalias ls

# print all shell options
shopt

# to unset (or stop) alias
shopt -u expand_aliases

# to set (or start) alias
shopt -s expand_aliases

echo $PATH
# list of directories separated by a colon

env

unset MYVAR

lsblk

partprobe

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

type python
# python is /usr/bin/python
# There are 5 different types, check using the 'type -f' flag
# 1. alias    (shell alias)
# 2. function (shell function, type will also print the function body)
# 3. builtin  (shell builtin)
# 4. file     (disk file)
# 5. keyword  (shell reserved word)

# You can also use `which`
which python
# /usr/bin/python

declare -F

du -hs .

# or
du -sb

cp -rp /path/to/directory

pushd .

# then pop
popd

# or use dirs to display the list of currently remembered directories.
dirs -l

df -h

# or
du -h

# or
du -sk /var/log/* |sort -rn |head -10

df -i
# Filesystem      Inodes  IUsed   IFree IUse% Mounted on
# devtmpfs        492652    304  492348    1% /dev
# tmpfs           497233      2  497231    1% /dev/shm
# tmpfs           497233    439  496794    1% /run
# tmpfs           497233     16  497217    1% /sys/fs/cgroup
# /dev/nvme0n1p1 5037976 370882 4667094    8% /
# tmpfs           497233      1  497232    1% /run/user/1000

df -TH

runlevel

init 3

# or
telinit 3

1. edit /etc/init/rc-sysinit.conf
2. env DEFAULT_RUNLEVEL=2

su

su somebody

repquota -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

# e.g. Mount /dev/sdb to /home/test
mount /dev/sdb /home/test

# e.g. Unmount /home/test
umount /home/test

mount
# or
df

cat /etc/passwd

getent passwd| awk '{FS="[:]"; print $1}'

compgen -u

compgen -g

group username

id username

# variable for UID
echo $UID

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

ldconfig -p

ldd /bin/ls

lastlog

last reboot

joe /etc/environment
# edit this file

ulimit -u

nproc --all

1. top
2. 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;
# or
yum install dconf dconf-editor;
yum install dbus dbus-x11;

# Check list
gsettings list-recursively

# Change some settings
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'

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 check with:
hostnamectl
# Or 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 on Red Hat:
yum list installed

apt list --upgradeable

# or
sudo yum check-update

sudo yum update --exclude=php*

lsof /mnt/dir

killall pulseaudio
# then press Alt-F2 and type in pulseaudio

lsscsi

telnet 192.168.2.106 53

ifconfig eth0 mtu 9000

pidof python

# or
ps aux|grep python

ps -p <PID>

# or
cat /proc/<PID>/status
cat /proc/<PID>/stack
cat /proc/<PID>/stat

# 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 don't have to type the whole program name
pgrep sublim

# pgrep, echo 1 if process found, echo 0 if no such process
pgrep -q sublime_text && echo 1 || echo 0

# top, takes longer time
top|grep sublime_text

# installation
# It collects the data every 10 minutes and generate its report daily. crontab file (/etc/cron.d/sysstat) is responsible for collecting and generating reports.
yum install sysstat
systemctl start sysstat
systemctl enable sysstat

# show CPU utilization 5 times every 2 seconds.
sar 2 5

# show memory  utilization 5 times every 2 seconds.
sar -r 2 5

# show paging statistics 5 times every 2 seconds.
sar -B 2 5

# To generate all network statistic:
sar -n ALL

# reading SAR log file using -f
sar -f /var/log/sa/sa31|tail

journalctl --file ./log/journal/a90c18f62af546ccba02fa3734f00a04/system.journal  --since "2020-02-11 00:00:00"

last

lastb

who

w

users

tail -f --pid=<PID> filename.txt
# replace <PID> with the process ID of the program.

systemctl list-unit-files|grep enabled

lshw -json >report.json
# Other options are: [ -html ]  [ -short ]  [ -xml ]  [ -json ]  [ -businfo ]  [ -sanitize ] ,etc

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

lsblk -f /dev/sdb

# or
sudo blkid /dev/sdb

uuidgen

lsblk -io KNAME,TYPE,MODEL,VENDOR,SIZE,ROTA
#where ROTA means rotational device / spinning hard disks (1 if true, 0 if false)

lspci
# List information about NIC
lspci | egrep -i --color 'network|ethernet'

lsusb

# Show the status of modules in the Linux Kernel
lsmod

# Add and remove modules from the Linux Kernel
modprobe

# or
# Remove a module
rmmod

# Insert a module
insmod

# Remotely finding out power status of the server
ipmitool -U <bmc_username> -P <bmc_password> -I lanplus -H <bmc_ip_address> power status

# Remotely switching on server
ipmitool -U <bmc_username> -P <bmc_password> -I lanplus -H <bmc_ip_address> power on

# Turn on panel identify light (default 15s)
ipmitool chassis identify 255

# Found out server sensor temperature
ipmitool sensors |grep -i Temp

# Reset BMC
ipmitool bmc reset cold

# Prnt BMC network
ipmitool lan print 1

# Setting BMC network
ipmitool -I bmc lan set 1 ipaddr 192.168.0.55
ipmitool -I bmc lan set 1 netmask 255.255.255.0
ipmitool -I bmc lan set 1 defgw ipaddr 192.168.0.1

dig +short www.example.net

# or
host www.example.net

curl http://checkip.amazonaws.com

dig -t txt www.example.net

# or
host -t txt www.example.net

ping 192.0.2.1 -t 10

traceroute example.net

nc -vw5 example.net 80
# Connection to example.net 80 port [tcp/http] succeeded!

nc -vw5 example.net 22
# nc: connect to example.net port 22 (tcp) timed out: Operation now in progress
# nc: connect to example.net port 22 (tcp) failed: Network is unreachable

# From server A:
$ sudo nc -l 80
# then you can connect to the 80 port from another server (e.g. server B):
# e.g. telnet <server A IP address> 80
# then type something in server B
# and you will see the result in server A!

# note that some companies might not like you using nmap
nmap -sT -O localhost

# check port 0-65535
nmap  -p0-65535 localhost

# skips checking if the host is alive which may sometimes cause a false positive and stop the scan.
$ nmap example.net -Pn

# Example output:
# Starting Nmap 7.01 ( https://nmap.org ) at 2020-07-18 22:59 CST
# Nmap scan report for example.net (172.217.24.14)
# Host is up (0.013s latency).
# Other addresses for example.net (not scanned): 2404:6800:4008:802::200e
# rDNS record for 172.217.24.14: tsa01s07-in-f14.1e100.net
# Not shown: 998 filtered ports
# PORT    STATE SERVICE
# 80/tcp  open  http
# 443/tcp open  https
#
# Nmap done: 1 IP address (1 host up) scanned in 3.99 seconds

$ nmap -A -T4 scanme.nmap.org
# -A to enable OS and version detection, script scanning, and traceroute; -T4 for faster execution

whois example.net

openssl s_client -showcerts -connect www.example.net:443

ip a

ip r

ip n

ip address add 192.168.140.3/24 dev eno16777736

sudo vi /etc/sysconfig/network-scripts/ifcfg-enoxxx
# then edit the fields: BOOTPROT, DEVICE, IPADDR, NETMASK, GATEWAY, DNS1 etc

sudo nmcli c reload

sudo systemctl restart network.service

hostnamectl

hostnamectl set-hostname "mynode"

curl -I http://example.net/
# HTTP/1.1 200 OK
# Server: nginx
# Date: Thu, 02 Jan 2020 07:01:07 GMT
# Content-Type: text/html
# Content-Length: 1119
# Connection: keep-alive
# Vary: Accept-Encoding
# Last-Modified: Mon, 09 Sep 2019 10:37:49 GMT
# ETag: "xxxxxx"
# Accept-Ranges: bytes
# Vary: Accept-Encoding

curl -v -o /dev/null -s -w 'Total: %{time_total}s\n' google.com

curl -s -o /dev/null -w "%{http_code}" https://www.example.net

curl -s -o /dev/null -w "%{redirect_url}" https://bit.ly/34EFwWC

# server side:
$ sudo iperf -s -p 80

# client side:
iperf -c <server IP address> --parallel 2 -i 1 -t 2 -p 80

sudo iptables -A INPUT -p tcp --dport 80 -j DROP

# only block connection from an IP address
sudo iptables –A INPUT –s <IP> -p tcp –dport 80 –j DROP

# If file is not specified, the file /usr/share/dict/words is used.
look phy|head -n 10
# phycic
# Phyciodes
# phycite
# Phycitidae
# phycitol
# phyco-
# phycochrom
# phycochromaceae
# phycochromaceous
# phycochrome

printf 'hello world\n%.0s' {1..5}

username=`echo -n "bashoneliner"`

tee <fileA fileB fileC fileD >/dev/null

tr -dc '[:print:]' < filename

tr --delete '\n' <input.txt >output.txt

tr '\n' ' ' <filename

tr /a-z/ /A-Z/

echo 'something' |tr a-z a
# aaaaaaaaa

diff fileA fileB
# a: added; d:delete; c:changed

# or
sdiff fileA fileB
# side-to-side merge of file differences

diff fileA fileB --strip-trailing-cr

# having two sorted and uniqed files (for example after running `$ sort -uo fileA fileA` and same for fileB):
# ------
# fileA:
# ------
# joey
# kitten
# piglet
# puppy
# ------
# fileB:
# ------
# calf
# chick
# joey
# puppy
#
# Find lines in both files
comm -12 fileA fileB
# joey
# puppy
#
# Find lines in fileB that are NOT in fileA
comm -13 fileA fileB
# calf
# chick
#
# Find lines in fileA that are NOT in fileB
comm -23 fileA fileB
# kitten
# piglet

nl fileA

# or
nl -nrz fileA
# add leading zeros

# or
nl -w1 -s ' '
# making it simple, blank separate

# fileA and fileB should have the same ordering of lines.
join -t '\t' fileA fileB

# Join using specified field (e.g. column 3 of fileA and column 5 of fileB)
join -1 3 -2 5 fileA fileB

paste fileA fileB fileC
# default tab separate

# 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

echo 12345| rev

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 '

# Split by line (e.g. 1000 lines/smallfile)
split -d -l 1000 largefile.txt

# Split by byte without breaking lines across files
split -C 10 largefile.txt

#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'

head -c 50 filename

cat file|rev | cut -d/ -f1 | rev

((var++))
# or
var=$((var+1))

cat filename|rev|cut -f1|rev

cat >myfile
let me add sth here
# exit with ctrl+d

# or using tee
tee myfile
let me add sth else here
# exit with ctrl+d

cat >>myfile
let me add sth here
# exit with ctrl+d

# or
cat << EoF >> filename
> add something here
> EoF 

# or using tee
tee -a myfile
let me add sth else here
# exit with ctrl+d

>filename

echo 'hihi' >>filename

# 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')
cat file.json | jq '.url'

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

echo 'hihihihi' | tee outputfile.txt
# use '-a' with tee to append to file.

cat -v filename

expand filename

unexpand filename

od filename

tac filename

while read a b; do yes $b |head -n $a ; done <test.txt

identify myimage.png
#myimage.png PNG 1049x747 1049x747+0+0 8-bit sRGB 1.006MB 0.000u 0:00.000

complete -W "now tomorrow never" dothis
# ~$ dothis  
# never     now       tomorrow
# press 'tab' again to auto-complete after typing 'n' or 't'

# print the current month, today will be highlighted.
cal
# October 2019      
# Su Mo Tu We Th Fr Sa  
#    1  2  3  4  5  
# 6  7  8  9 10 11 12  
# 13 14 15 16 17 18 19  
# 20 21 22 23 24 25 26  
# 27 28 29 30 31  

# only display November
cal -m 11

openssl md5 -binary /path/to/file| base64
# NWbeOpeQbtuY0ATWuUeumw==

export LC_ALL=C

# to revert:
unset LC_ALL

echo test|base64
#dGVzdAo=

dirname `pwd`

zmore filename

# or
zless filename

some_commands  &>log &

# or
some_commands 2>log &

# or
some_commands 2>&1| tee logfile

# or
some_commands |& tee logfile

# or
some_commands 2>&1 >>outfile
#0: standard input; 1: standard output; 2: standard error

# run sequentially
(sleep 2; sleep 3) &

# run parallelly
sleep 2 & sleep 3 &

# e.g. Run myscript.sh even when log out.
nohup bash myscript.sh

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

speaker-test -t sine -f 1000 -l1

(speaker-test -t sine -f 1000) & pid=$!;sleep 0.1s;kill -9 $pid

history -w
vi ~/.bash_history
history -r

# or
history -d [line_number]

# list 5 previous command (similar to `history |tail -n 5` but wont print the history command itself)
fc -l -5

Ctrl+U

# or
Ctrl+C

# or
Alt+Shift+#
# to make it to history

# addmetodistory
# just add a "#" before~~

head !$

clear
# or simply Ctrl+l

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!)

cd $(mktemp -d)
# for example, this will create a temporary directory "/tmp/tmp.TivmPLUXFT"

mkdir -p project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat}
# -p: make parent directory
# this will create:
# project/
# project/bin/
# project/demo/
# project/demo/stat/
# project/doc/
# project/doc/html/
# project/doc/info/
# project/doc/pdf/
# project/lib/
# project/lib/ext/
# project/src/
#
# project/
# ├── bin
# ├── demo
# │   └── stat
# ├── doc
# │   ├── html
# │   ├── info
# │   └── pdf
# ├── lib
# │   └── ext
# └── src

cd tmp/ && tar xvf ~/a.tar

cd tmp/a/b/c ||mkdir -p tmp/a/b/c

cd tmp/a/b/c \
> || \
>mkdir -p tmp/a/b/c

file /tmp/
# tmp/: directory

#!/bin/bash
file=${1#*.}
# remove string before a "."

python -m SimpleHTTPServer
# or when using python3:
python3 -m http.server

read input
echo $input

declare -a array=()

# or
declare array=()

# or associative array
declare -A array=()

scp -r directoryname user@ip:/path/to/send

# Don't try this at home!
# It is a function that calls itself twice every call until you run out of system resources.
# A '# ' is added in front for safety reason, remove it when seriously you are testing it.
# :(){:|:&};:

# Don't try this at home! 
echo c > /proc/sysrq-trigger

!$

echo $?

unxz filename.tar.xz
# then
tar -xf filename.tar

tar xvfj file.tar.bz2

unxz file.tar.xz
tar xopf file.tar

tar xvf -C /path/to/directory filename.gz

# First cd to the directory, they run:
zip -r -D ../myzipfile .
# you will see the myzipfile.zip in the parent directory (cd ..)

# 'y':
yes

# or 'n':
yes n

# or 'anything':
yes anything

# pipe yes to other command
yes | rm -r large_directory

fallocate -l 10G 10Gigfile

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

watch -n 1 wc -l filename

# These options can make your code safer but, depending on how your pipeline is written, it might be too aggressive 
# or it might not catch the errors that you are interested in

# for reference see https://gist.github.com/mohanpedala/1e2ff5661761d3abd0385e8223e16425
#               and https://mywiki.wooledge.org/BashPitfalls#set_-euo_pipefail

set -o errexit      # exit immediately if a pipeline returns a non-zero status
set -o errtrace     # trap ERR from shell functions, command substitutions, and commands from subshell
set -o nounset      # treat unset variables as an error
set -o pipefail     # pipe will exit with last non-zero status, if applicable
set -Eue -o pipefail  # shorthand for above (pipefail has no short option)

set -x; echo `expr 10 + 20 `
# or
set -o xtrace; echo `expr 10 + 20 `

# to turn it off..
set +x

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

# Create a screen and name it 'test'
screen -S test

# Create detached session foo:
screen -S foo -d -m

# Detached session foo:
screen: ^a^d

# List sessions:
screen -ls

# Attach last session:
screen -r

# Attach to session foo:
screen -r foo

# Kill session foo:
screen -r foo -X quit


# Scroll:
# 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.  

# Create session and attach:
tmux

# Attach to session foo:
tmux attach -t foo

# Detached session foo:
^bd

# List sessions:
tmux ls

# Attach last session:
tmux attach

# Kill session foo:
tmux kill-session -t foo

# Create detached session foo:
tmux new -s foo -d

# Send command to all panes in tmux:
Ctrl-B
:setw synchronize-panes

# Some tmux pane control commands:
Ctrl-B
#   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

#   Distribute Vertically (rows):
select-layout even-vertical
#   or
Ctrl+b, Alt+2

# Distribute horizontally (columns):
select-layout even-horizontal
#   or
Ctrl+b, Alt+1

# Scroll
Ctrl-b then \[ then you can use your normal navigation keys to scroll around.
Press q to quit scroll mode.

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 -d */

ls -1
# or list all, do not ignore entries starting with .
ls -1a

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:
# home/
# └── project
#     ├── 1
#     ├── 2
#     ├── 3
#     ├── 4
#     └── 5
#

# set level directories deep (e.g. level 1)
tree -L 1
# home/
# └── project

# 1. install virtualenv.
sudo apt-get install virtualenv
# 2. Create 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
# 6. Exit virtual environment
deactivate