30-04-2021

Shell Cheat Sheet



KORN SHELL PROGRAMMING CHEAT SHEET Special Characters Metacharacters have special meaning to the shell unless quoted (by preceding it with a or enclosing it in ` `) Inside double quotes “ “ parameter and command substitution occur and quotes characters `”$. Bash cheat sheet: Top 25 commands and creating custom commands. Which tell the shell how to behave as a user works at the command line or in scripts. Windows PowerShell Commands Cheat Sheet We break down what Windows PowerShell is, and provide you a definitive downloadable PowerShell Commands Cheat Sheet (PDF) as a quick reference to get you started and running your own commands. Tim Keary Network administration expert UPDATED: March 31, 2021. Reads and executes commands from a designated file in the current shell. Suspend: Suspends the execution of the shell until a SIGCONT signal is received. Test: Returns an exit status of 0 or 1 based on the specified condition. Times: Displays the accumulated user and system shell time.

  1. Shell Cheat Sheet Pentestmonkey
  2. Linux Shell Cheat Sheet Pdf
  3. Mongo Shell Cheat Sheet

Explain shell commands

Basics

Redirection

Redirect std and err output to /dev/null:

Redirect to stderr:

Use tee to redirect to a file and stdout:

stderr + /dev/tty0:

stderr + syslog

Log bash script output

Put this on top of your bash script:

Echo to stderr

Batch Rename Files

-n = dry run

rename -n 's/_bottom/_x/' *.png

rename -n 's/.htm$/.html/' *.htm

Add a prefix

rename -n 's/^/PRE_/' *

Add a suffix

sudo rename -n 's/$/.conf/' /etc/apache2/sites-available/*

Compare files in two directories

Not the content!

diff -qr dir1/ dir2/

Search for a string in files recusevly

grep -r 'word' .

Batch search and replace in files

sed -i 's/my_search/my_replace/g' *.html

Sed replace with regular expression

sed -E 's/ root@[a-zA-Z0-9]+$/ root@foo/' /etc/ssh/ssh_host_rsa_key.pub

Sed delete line by regular expression

sed -i '/root@host.example.com$/d' /root/.ssh/authorized_keys

Recursive

find . -name '*.php' | xargs -n 1 sed -i -e 's|Theme' . sfConfig::get('app_theme_package', 'NG') . 'Plugin|Plugin|g'

Find Symlinks

find ./ -type l -exec ls -l {} ;

find . -type l

Find multiple file types

Note the spaces after and before the braces

find . ( -name '*.php' -or -name '*.html' -or -name '*.css' -or -name '*.js' ) -exec ls -la {} ;

Find files older than x days

find /my/dir -type f -mtime +7 | xargs ls -l

Extract columns/fields

  • du ./* -shx | cut -c 1-3
    • Characters 1-3
  • du ./* -shx | awk '{print $2}'
    • Second column separated by whitespace
  • echo 'hey whats up with you' | | awk '{for (i=3; i<NF; i++) printf $i ' '; print $NF}'
    • Get all remaining columns starting from column 3

Return Code / Exit Status

Print the return code of the last command. 0=success, >0=failure

echo $?

Test exit status

Run multiple commands even with errors, but 'log' occurence of error:

For longer/more complex shell scripts the following is recommended:

Return Code Condition

Variables

Multiline options with comments

Explanation:

  • A backslash ' at the end of the line allows to break a line into multiple lines. Make sure there is no whitspace (spaces,...) after the backslash!
  • Everything inside '`' backticks is executed. We use this trick for comments with '#'

Assign heredoc EOF to Variable

If clauses

If string contains...

Combine clauses

Repeat until it works

until ssh user@server.test; do echo 'Nope'; sleep 2; done

Test multiple script arguments

Test if multiple variables are set

Confirmation

Search and replace in a file

Sed search and replace from stdin

  • echo -n 'foo' | sed -e '/.*search/{r /dev/stdin' -e 'd;}' /my/file

or direct replace in file:

Shell Cheat Sheet
  • echo -n 'foo' | sed -i -e '/.*search/{r /dev/stdin' -e 'd;}' /my/file

Create user by script

Find and iterate

Iterate lines in a variable

Iterate Mysql result

Check if a mount point/disk is mounted

Echo tabs

  • echo -e 'Heytwhatstup'

Check if a website is running correctly

Can be used in cron like this, sends an email in case of error if you configure 'MAILTO=me@example.com' option in crontab.
You need also SHELL=/bin/bash

if [[ `wget -q --no-check-certificate -O - https://example.com:1234/xyz/ | grep 'Ok Text'` ' ]]; then echo 'example.com website is running correcly!'; fi

Check if a remote service is running correctly

Can be used in cron like this, sends an email in case of error if you configure 'MAILTO=me@example.com' option in crontab
You need also SHELL=/bin/bash

nc -z example.com 1234; if [[ $? != 0 ]]; then echo 'Service 1234 is not running on example.com!'; fi
Explanation: nc = netcat, '$?' checks the return code of the 'nc' command. If not '0' (not ok) perform notifying.

Logging to stderr and syslog

logger -s 'ERROR: no more haribos!'

Shell Cheat Sheet

Gernerate random string

cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 6 | head -n 1

Send email to root

echo -e 'huhunhaha' | mail -s 'Test subj' root

Get local ip

ip route get 1.1.1.1 | head -1 | cut -d ' ' -f8

  • Created by Klemens Ullmann-Marx, 07/01/2009 09:58:39
  • Updated by Klemens Ullmann-Marx, 02/16/2021 10:51:09
  • Read access: Everyone, WikiAdmins, Logged in users | Write access: WikiAdmins, Logged in users
  • Read counter: 18293 | Edit counter: 71
  • Tags: bash

Explain shell commands

Basics

Redirection

Redirect std and err output to /dev/null:

Redirect to stderr:

Use tee to redirect to a file and stdout:

stderr + /dev/tty0:

stderr + syslog

Log bash script output

Put this on top of your bash script:

Echo to stderr

Batch Rename Files

-n = dry run

rename -n 's/_bottom/_x/' *.png

rename -n 's/.htm$/.html/' *.htm

Add a prefix

rename -n 's/^/PRE_/' *

Add a suffix

sudo rename -n 's/$/.conf/' /etc/apache2/sites-available/*

Compare files in two directories

Not the content!

diff -qr dir1/ dir2/

Search for a string in files recusevly

grep -r 'word' .

Batch search and replace in files

sed -i 's/my_search/my_replace/g' *.html

Sed replace with regular expression

sed -E 's/ root@[a-zA-Z0-9]+$/ root@foo/' /etc/ssh/ssh_host_rsa_key.pub

Sed delete line by regular expression

sed -i '/root@host.example.com$/d' /root/.ssh/authorized_keys

Recursive

find . -name '*.php' | xargs -n 1 sed -i -e 's|Theme' . sfConfig::get('app_theme_package', 'NG') . 'Plugin|Plugin|g'

Find Symlinks

find ./ -type l -exec ls -l {} ;

find . -type l

Find multiple file types

Note the spaces after and before the braces

find . ( -name '*.php' -or -name '*.html' -or -name '*.css' -or -name '*.js' ) -exec ls -la {} ;

Find files older than x days

find /my/dir -type f -mtime +7 | xargs ls -l

Extract columns/fields

  • du ./* -shx | cut -c 1-3
    • Characters 1-3
  • du ./* -shx | awk '{print $2}'
    • Second column separated by whitespace
  • echo 'hey whats up with you' | | awk '{for (i=3; i<NF; i++) printf $i ' '; print $NF}'
    • Get all remaining columns starting from column 3

Return Code / Exit Status

Print the return code of the last command. 0=success, >0=failure

echo $?

Test exit status

Run multiple commands even with errors, but 'log' occurence of error:

For longer/more complex shell scripts the following is recommended:

Return Code Condition

Variables

Multiline options with comments

Explanation:

  • A backslash ' at the end of the line allows to break a line into multiple lines. Make sure there is no whitspace (spaces,...) after the backslash!
  • Everything inside '`' backticks is executed. We use this trick for comments with '#'

Assign heredoc EOF to Variable

If clauses

If string contains...

Combine clauses

Repeat until it works

until ssh user@server.test; do echo 'Nope'; sleep 2; done

Test multiple script arguments

Shell Cheat Sheet Pentestmonkey

Test if multiple variables are set

Confirmation

Search and replace in a file

Sed search and replace from stdin

  • echo -n 'foo' | sed -e '/.*search/{r /dev/stdin' -e 'd;}' /my/file

or direct replace in file:

  • echo -n 'foo' | sed -i -e '/.*search/{r /dev/stdin' -e 'd;}' /my/file

Create user by script

Find and iterate

Iterate lines in a variable

Iterate Mysql result

Check if a mount point/disk is mounted

Echo tabs

  • echo -e 'Heytwhatstup'

Check if a website is running correctly

Can be used in cron like this, sends an email in case of error if you configure 'MAILTO=me@example.com' option in crontab.
You need also SHELL=/bin/bash

if [[ `wget -q --no-check-certificate -O - https://example.com:1234/xyz/ | grep 'Ok Text'` ' ]]; then echo 'example.com website is running correcly!'; fi

Check if a remote service is running correctly

Can be used in cron like this, sends an email in case of error if you configure 'MAILTO=me@example.com' option in crontab
You need also SHELL=/bin/bash

nc -z example.com 1234; if [[ $? != 0 ]]; then echo 'Service 1234 is not running on example.com!'; fi
Explanation: nc = netcat, '$?' checks the return code of the 'nc' command. If not '0' (not ok) perform notifying.

Logging to stderr and syslog

logger -s 'ERROR: no more haribos!'

Gernerate random string

cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 6 | head -n 1

Send email to root

echo -e 'huhunhaha' | mail -s 'Test subj' root

Linux Shell Cheat Sheet Pdf

Get local ip

ip route get 1.1.1.1 | head -1 | cut -d ' ' -f8

Mongo Shell Cheat Sheet

  • Created by Klemens Ullmann-Marx, 07/01/2009 09:58:39
  • Updated by Klemens Ullmann-Marx, 02/16/2021 10:51:09
  • Read access: Everyone, WikiAdmins, Logged in users | Write access: WikiAdmins, Logged in users
  • Read counter: 18295 | Edit counter: 71
  • Tags: bash