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README.md
@ -1,7 +1,7 @@
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# Bash-Oneliner
|
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I am glad that you are here! I was working on bioinformatics a few years ago and was amazed by those single-word bash commands which are much faster than my dull scripts, time saved through learning command-line shortcuts and scripting. Recent years I am working on cloud computing and I keep recording those useful commands here. Not all of them is oneliner, but i put effort on making them brief and swift. I am mainly using Ubuntu, Amazon Linux, RedHat, Linux Mint, Mac and CentOS, sorry if the commands don't work on your system.
|
||||
|
||||
This blog will focus on simple bash commands for parsing data and Linux system maintenance that i acquired from work and LPIC exam. I apologize that there are no detailed citation for all the commands, but they are probably from dear Google and Stack Overflow.
|
||||
This blog will focus on simple bash commands for parsing data and Linux system maintenance that i acquired from work and LPIC exam. 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, please correct me anytime, thank you.
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If you know other cool commands, please teach me!
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@ -12,13 +12,13 @@ Here's a more stylish version of [Bash-Oneliner](https://onceupon.github.io/Bash
|
||||
|
||||
- [Terminal Tricks](#terminal-tricks)
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||||
- [Variable](#variable)
|
||||
- [Math](#math)
|
||||
- [Grep](#grep)
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||||
- [Sed](#sed)
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||||
- [Awk](#awk)
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||||
- [Xargs](#xargs)
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||||
- [Find](#find)
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||||
- [Condition and Loop](#condition-and-loop)
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- [Math](#math)
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- [Time](#time)
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- [Download](#download)
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||||
- [Random](#random)
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@ -57,7 +57,7 @@ Esc + u
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Esc + l
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# converts text from cursor to the end of the word to lowercase.
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Esc + c
|
||||
# converts letter under the cursor to uppercase, rest of the word to lowercase.
|
||||
# converts letter under the cursor to uppercase.
|
||||
```
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||||
##### Run history number (e.g. 53)
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||||
```bash
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||||
@ -69,6 +69,7 @@ Esc + c
|
||||
!!
|
||||
# run the previous command using sudo
|
||||
sudo !!
|
||||
# of course you need to enter your password
|
||||
```
|
||||
|
||||
##### Run last command and change some parameter using caret substitution (e.g. last command: echo 'aaa' -> rerun as: echo 'bbb')
|
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@ -97,16 +98,16 @@ sudo !!
|
||||
##### Bash globbing
|
||||
```bash
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||||
# '*' serves as a "wild card" for filename expansion.
|
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/etc/pa*wd #/etc/passwd
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||||
|
||||
# '?' serves as a single-character "wild card" for filename expansion.
|
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/b?n/?at #/bin/cat
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|
||||
# '[]' serves to match the character from a range.
|
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# '?' serves as a single-character "wild card" for filename expansion.
|
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/etc/pa*wd #/etc/passwd
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|
||||
# ‘[]’ serves to match the character from a range.
|
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ls -l [a-z]* #list all files with alphabet in its filename.
|
||||
|
||||
# '{}' can be used to match filenames with more than one patterns
|
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ls *.{sh,py} #list all .sh and .py files
|
||||
# ‘{}’ can be used to match filenames with more than one patterns
|
||||
ls {*.sh,*.py} #list all .sh and .py files
|
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```
|
||||
|
||||
##### Some handy environment variables
|
||||
@ -134,19 +135,9 @@ $HOSTNAME current hostname
|
||||
##### Variable substitution within quotes
|
||||
```bash
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# foo=bar
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echo $foo
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# bar
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echo "$foo"
|
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# bar
|
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# single quotes cause variables to not be expanded
|
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echo '$foo'
|
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# $foo
|
||||
# single quotes within double quotes will not cancel expansion and will be part of the output
|
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echo "'$foo'"
|
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# 'bar'
|
||||
# doubled single quotes act as double quotes making variables expand
|
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echo ''$foo''
|
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# bar
|
||||
echo "'$foo'"
|
||||
#'bar'
|
||||
# double/single quotes around single quotes make the inner single quotes expand variables
|
||||
```
|
||||
##### Get the length of variable
|
||||
```bash
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||||
@ -187,13 +178,11 @@ echo ${var[@]#0}
|
||||
```bash
|
||||
{var//a/,}
|
||||
```
|
||||
|
||||
##### Grep lines with strings from a file (e.g. lines with 'stringA or 'stringB' or 'stringC')
|
||||
```bash
|
||||
#with grep
|
||||
test="stringA stringB stringC"
|
||||
grep ${test// /\\\|} file.txt
|
||||
# turning the space into 'or' (\|) in grep
|
||||
test="god the father"
|
||||
grep ${test// /\\\|} file.txt
|
||||
# turning the space into 'or' (\|) in grep
|
||||
```
|
||||
|
||||
##### To change the case of the string stored in the variable to lowercase (Parameter Expansion)
|
||||
@ -216,9 +205,9 @@ echo "$bar" # foo
|
||||
```bash
|
||||
echo $(( 10 + 5 )) #15
|
||||
x=1
|
||||
echo $(( x++ )) #1 , notice that it is still 1, since it's post-increment
|
||||
echo $(( x++ )) #1 , notice that it is still 1, since it's post-incremen
|
||||
echo $(( x++ )) #2
|
||||
echo $(( ++x )) #4 , notice that it is not 3 since it's pre-increment
|
||||
echo $(( ++x )) #4 , notice that it is not 3 since it's pre-incremen
|
||||
echo $(( x-- )) #4
|
||||
echo $(( x-- )) #3
|
||||
echo $(( --x )) #1
|
||||
@ -276,7 +265,7 @@ echo "var=5;--var"| bc
|
||||
##### Type of grep
|
||||
```bash
|
||||
grep = grep -G # Basic Regular Expression (BRE)
|
||||
fgrep = grep -F # fixed text, ignoring meta-characters
|
||||
fgrep = grep -F # fixed text, ignoring meta-charachetrs
|
||||
egrep = grep -E # Extended Regular Expression (ERE)
|
||||
pgrep = grep -P # Perl Compatible Regular Expressions (PCRE)
|
||||
rgrep = grep -r # recursive
|
||||
@ -291,15 +280,15 @@ grep -c "^$"
|
||||
```bash
|
||||
grep -o '[0-9]*'
|
||||
#or
|
||||
grep -oP '\d*'
|
||||
grep -oP '\d'
|
||||
```
|
||||
##### Grep integer with certain number of digits (e.g. 3)
|
||||
```bash
|
||||
grep '[0-9]\{3\}'
|
||||
grep ‘[0-9]\{3\}’
|
||||
# or
|
||||
grep -E '[0-9]{3}'
|
||||
grep -E ‘[0-9]{3}’
|
||||
# or
|
||||
grep -P '\d{3}'
|
||||
grep -P ‘\d{3}’
|
||||
```
|
||||
|
||||
##### Grep only IP address
|
||||
@ -406,14 +395,14 @@ grep 'A\|B\|C\|D'
|
||||
grep 'A.*B'
|
||||
```
|
||||
|
||||
##### Regex any single character (e.g. ACB or AEB)
|
||||
##### Regex any singer character (e.g. ACB or AEB)
|
||||
```bash
|
||||
grep 'A.B'
|
||||
```
|
||||
|
||||
##### Regex with or without a certain character (e.g. color or colour)
|
||||
```bash
|
||||
grep 'colou\?r'
|
||||
grep ‘colou?r’
|
||||
```
|
||||
|
||||
##### Grep all content of a fileA from fileB
|
||||
@ -467,10 +456,9 @@ sed 1,100d filename
|
||||
##### Remove lines with string (e.g. 'bbo')
|
||||
```bash
|
||||
sed "/bbo/d" filename
|
||||
# case insensitive:
|
||||
- case insensitive:
|
||||
sed "/bbo/Id" filename
|
||||
```
|
||||
|
||||
##### Remove lines whose nth character not equal to a value (e.g. 5th character not equal to 2)
|
||||
```bash
|
||||
sed -E '/^.{5}[^2]/d'
|
||||
@ -522,7 +510,7 @@ sed -i '1s/^/[/' file
|
||||
|
||||
##### Add string at certain line number (e.g. add 'something' to line 1 and line 3)
|
||||
```bash
|
||||
sed -e '1isomething' -e '3isomething'
|
||||
sed -e '1isomething -e '3isomething'
|
||||
```
|
||||
|
||||
##### Add string to end of file (e.g. "]")
|
||||
@ -549,7 +537,7 @@ sed -e 's/$/\}\]/' filename
|
||||
sed 's/.\{4\}/&\n/g'
|
||||
```
|
||||
|
||||
##### Concatenate/combine/join files with a separator and next line (e.g separate by ",")
|
||||
##### Concatenate/combine/join files with a seperator and next line (e.g separate by ",")
|
||||
```bash
|
||||
sed -s '$a,' *.json > all.json
|
||||
```
|
||||
@ -617,12 +605,12 @@ sed "s/$/\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 $(ls);do sed -i "s/$/\t$i/" $i;done
|
||||
```
|
||||
|
||||
##### Add extension of filename to last column
|
||||
```bash
|
||||
for i in T000086_1.02.n T000086_1.02.p; do sed "s/$/\t${i/*./}/" $i; done >T000086_1.02.np
|
||||
for i in T000086_1.02.n T000086_1.02.p;do sed "s/$/\t${i/*./}/" $i;done >T000086_1.02.np
|
||||
```
|
||||
|
||||
##### Remove newline\ nextline
|
||||
@ -786,7 +774,7 @@ awk '{printf("%s\t%s\n",NR,$0)}'
|
||||
|
||||
##### Break combine column data into rows
|
||||
```bash
|
||||
# For example, separate the following content:
|
||||
# For example, seperate the following content:
|
||||
# David cat,dog
|
||||
# into
|
||||
# David cat
|
||||
@ -906,7 +894,7 @@ find /dir/to/A -type f -name "*.py" -print 0| xargs -0 -r -I file cp -v -p file
|
||||
|
||||
##### With sed
|
||||
```bash
|
||||
ls |xargs -n1 -I file sed -i '/^Pos/d' file
|
||||
ls |xargs -n1 -I file sed -i '/^Pos/d' filename
|
||||
```
|
||||
|
||||
##### Add the file name to the first line of file
|
||||
@ -994,11 +982,6 @@ find . -type f -empty
|
||||
find . -type f -empty -delete
|
||||
```
|
||||
|
||||
##### Recursively count all the files in a directory
|
||||
```bash
|
||||
find . -type f | wc -l
|
||||
```
|
||||
|
||||
## Condition and loop
|
||||
[[back to top](#handy-bash-one-liners)]
|
||||
|
||||
@ -1008,7 +991,7 @@ find . -type f | wc -l
|
||||
if [[ "$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
|
||||
if grep -q hello myfile; then …
|
||||
|
||||
# Test if mydir is a directory, change to it and do other stuff:
|
||||
if cd mydir; then
|
||||
@ -1018,12 +1001,9 @@ else
|
||||
fi
|
||||
|
||||
# if variable is null
|
||||
if [ ! -s "myvariable" ]; then echo -e "variable is null!" ; fi
|
||||
if [ ! -s "myvariable" ]
|
||||
#True of the length if "STRING" is zero.
|
||||
|
||||
# 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
|
||||
@ -1037,17 +1017,16 @@ then
|
||||
fi
|
||||
|
||||
# Test if the value of x is greater or equal than 5
|
||||
if [ "$x" -ge 5 ]; then echo -e "greater or equal than 5!" ; fi
|
||||
if [ "$x" -ge 5 ]; then …
|
||||
|
||||
# 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
|
||||
if ((x >= 5)); then …
|
||||
|
||||
# Use (( )) for arithmetic operation
|
||||
if ((j==u+2)); then echo -e "j==u+2!!" ; fi
|
||||
if ((j==u+2))
|
||||
|
||||
# Use [[ ]] for comparison
|
||||
if [[ $age -gt 21 ]]; then echo -e "forever 21!!" ; fi
|
||||
|
||||
if [[ $age -gt 21 ]]
|
||||
```
|
||||
|
||||
[More if commands](http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_07_01.html)
|
||||
@ -1055,7 +1034,7 @@ if [[ $age -gt 21 ]]; then echo -e "forever 21!!" ; fi
|
||||
##### For loop
|
||||
```bash
|
||||
# Echo the file name under the current directory
|
||||
for i in $(ls); do echo file $i; done
|
||||
for i in $(ls); do echo file $i;done
|
||||
#or
|
||||
for i in *; do echo file $i; done
|
||||
|
||||
@ -1063,7 +1042,7 @@ for i in *; do echo file $i; done
|
||||
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
|
||||
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
|
||||
@ -1073,21 +1052,21 @@ while read -r line; do ...; done <myfile
|
||||
for line in $(cat myfile); do echo $line; read -n1; done
|
||||
|
||||
#Loop through an array
|
||||
for i in "${arrayName[@]}"; do echo $i; done
|
||||
for i in "${arrayName[@]}"; do echo $i;done
|
||||
|
||||
```
|
||||
|
||||
##### While loop,
|
||||
```bash
|
||||
# Column subtraction of a file (e.g. a 3 columns file)
|
||||
while read a b c; do echo $(($c-$b)); done < <(head filename)
|
||||
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
|
||||
while [[ $(pidof perl) ]];do echo f;sleep 10;done && python timetorunpython.py
|
||||
```
|
||||
|
||||
##### switch (case in bash)
|
||||
@ -1126,46 +1105,7 @@ date +%F
|
||||
|
||||
# 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 time point for N days ago or N days after
|
||||
```bash
|
||||
# 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
|
||||
#10-Apr-2020-21:54:40
|
||||
```
|
||||
|
||||
##### wait for random duration (e.g. sleep 1-5 second, like adding a jitter)
|
||||
@ -1278,7 +1218,7 @@ shuf -n 100 filename
|
||||
|
||||
##### Random order (lucky draw)
|
||||
```bash
|
||||
for i in a b c d e; do echo $i; done | shuf
|
||||
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)
|
||||
@ -1767,18 +1707,6 @@ du -h
|
||||
du -sk /var/log/* |sort -rn |head -10
|
||||
```
|
||||
|
||||
##### check the Inode utilization
|
||||
```
|
||||
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
|
||||
```
|
||||
|
||||
##### Show all file system type
|
||||
```bash
|
||||
df -TH
|
||||
@ -2093,7 +2021,7 @@ http://onceuponmine.blogspot.tw/2017/07/create-your-first-simple-daemon.html
|
||||
##### Tutorial for using your gmail to send email
|
||||
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)
|
||||
##### 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)
|
||||
```bash
|
||||
telnet 192.168.2.106 53
|
||||
```
|
||||
@ -2235,7 +2163,6 @@ sar -n ALL
|
||||
|
||||
# reading SAR log file using -f
|
||||
sar -f /var/log/sa/sa31|tail
|
||||
```
|
||||
|
||||
##### Reading from journal file
|
||||
```bash
|
||||
@ -2453,7 +2380,7 @@ nc -vw5 google.com 22
|
||||
# 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
|
||||
# e.g. telent <server A IP address> 80
|
||||
# then type something in server B
|
||||
# and you will see the result in server A!
|
||||
```
|
||||
@ -2561,16 +2488,6 @@ curl -I http://example.com/
|
||||
# Vary: Accept-Encoding
|
||||
```
|
||||
|
||||
##### Find out the http status code of a URL
|
||||
```bash
|
||||
curl -s -o /dev/null -w "%{http_code}" https://www.google.com
|
||||
```
|
||||
|
||||
##### Unshorten a shortended URL
|
||||
```bash
|
||||
curl -s -o /dev/null -w "%{redirect_url}" https://bit.ly/34EFwWC
|
||||
```
|
||||
|
||||
##### Perform network throughput tests
|
||||
```bash
|
||||
# server side:
|
||||
@ -2595,16 +2512,16 @@ sudo iptables –A INPUT –s <IP> -p tcp –dport 80 –j DROP
|
||||
```bash
|
||||
# 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
|
||||
# Phil
|
||||
# Philadelphia
|
||||
# Philadelphia's
|
||||
# Philby
|
||||
# Philby's
|
||||
# Philip
|
||||
# Philippe
|
||||
# Philippe's
|
||||
# Philippians
|
||||
# Philippine
|
||||
```
|
||||
|
||||
##### Repeat printing string n times (e.g. print 'hello world' five times)
|
||||
@ -2659,41 +2576,7 @@ sdiff fileA fileB
|
||||
|
||||
##### Compare two files, strip trailing carriage return/ nextline (e.g. fileA, fileB)
|
||||
```bash
|
||||
diff fileA fileB --strip-trailing-cr
|
||||
```
|
||||
|
||||
##### Find common/differing lines
|
||||
```bash
|
||||
# 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
|
||||
diff fileA fileB --strip-trailing-cr
|
||||
```
|
||||
|
||||
##### Number a file (e.g. fileA)
|
||||
@ -2769,8 +2652,8 @@ echo {1,2}{1,2}
|
||||
```bash
|
||||
set = {A,T,C,G}
|
||||
group= 5
|
||||
for ((i=0; i<$group; i++)); do
|
||||
repetition=$set$repetition; done
|
||||
for ((i=0; i<$group; i++));do
|
||||
repetition=$set$repetition;done
|
||||
bash -c "echo "$repetition""
|
||||
```
|
||||
|
||||
@ -2860,28 +2743,12 @@ var=$((var+1))
|
||||
cat filename|rev|cut -f1|rev
|
||||
```
|
||||
|
||||
##### Create or replace a file with contents
|
||||
##### Cat to a file
|
||||
```bash
|
||||
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
|
||||
```
|
||||
|
||||
##### Append to a file with contents
|
||||
```bash
|
||||
cat >>myfile
|
||||
let me add sth here
|
||||
# exit with ctrl+d
|
||||
|
||||
# or using tee
|
||||
tee -a myfile
|
||||
let me add sth else here
|
||||
# exit with ctrl+d
|
||||
exit by control + c
|
||||
^C
|
||||
```
|
||||
|
||||
##### Clear the contents of a file (e.g. filename)
|
||||
@ -2964,7 +2831,7 @@ tac filename
|
||||
|
||||
##### Reverse the result from `uniq -c`
|
||||
```bash
|
||||
while read a b; do yes $b |head -n $a ; done <test.txt
|
||||
while read a b; do yes $b |head -n $a ;done <test.txt
|
||||
```
|
||||
|
||||
|
||||
@ -3000,13 +2867,6 @@ cal
|
||||
# only display November
|
||||
cal -m 11
|
||||
```
|
||||
|
||||
##### Convert the hexadecimal MD5 checksum value into its base64-encoded format.
|
||||
```bash
|
||||
openssl md5 -binary /path/to/file| base64
|
||||
# NWbeOpeQbtuY0ATWuUeumw==
|
||||
```
|
||||
|
||||
##### Forces applications to use the default language for output
|
||||
```bash
|
||||
export LC_ALL=C
|
||||
@ -3228,7 +3088,7 @@ scp -r directoryname user@ip:/path/to/send
|
||||
echo $?
|
||||
```
|
||||
|
||||
##### Extract .xz
|
||||
##### Extract .xf
|
||||
```
|
||||
unxz filename.tar.xz
|
||||
# then
|
||||
@ -3268,7 +3128,8 @@ yes n
|
||||
# or 'anything':
|
||||
yes anything
|
||||
|
||||
# pipe yes to other command
|
||||
# For example:
|
||||
```bash
|
||||
yes | rm -r large_directory
|
||||
```
|
||||
|
||||
@ -3279,9 +3140,9 @@ fallocate -l 10G 10Gigfile
|
||||
|
||||
##### Create dummy file of certain size (e.g. 200mb)
|
||||
```bash
|
||||
dd if=/dev/zero of=/dev/shm/200m bs=1024k count=200
|
||||
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
|
||||
dd if=/dev/zero of=//dev/shm/200m bs=1M count=200
|
||||
|
||||
# Standard output:
|
||||
# 200+0 records in
|
||||
@ -3294,29 +3155,9 @@ dd if=/dev/zero of=/dev/shm/200m bs=1M count=200
|
||||
watch -n 1 wc -l filename
|
||||
```
|
||||
|
||||
##### Use Bash Strict Mode
|
||||
```bash
|
||||
# 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)
|
||||
```
|
||||
|
||||
##### Print commands and their arguments when execute (e.g. echo `expr 10 + 20 `)
|
||||
```bash
|
||||
set -x; echo `expr 10 + 20 `
|
||||
# or
|
||||
set -o xtrace; echo `expr 10 + 20 `
|
||||
|
||||
# to turn it off..
|
||||
set +x
|
||||
```
|
||||
|
||||
##### Print some meaningful sentences to you (install fortune first)
|
||||
@ -3347,9 +3188,6 @@ 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
|
||||
|
||||
@ -3368,17 +3206,16 @@ 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 ↓).
|
||||
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'
|
||||
(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.
|
||||
Ctrl+A, Shift+H
|
||||
# You will then find a screen.log file under current directory.
|
||||
```
|
||||
|
||||
##### Using Tmux for multiple terminal sessions
|
||||
@ -3504,8 +3341,6 @@ source .venv/bin/activate
|
||||
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
|
||||
```
|
||||
|
||||
|
||||
|
||||
Reference in New Issue
Block a user