bash Cheat Sheet

basic bash commands

pwd : print working directory

cd /path/to/dir : change direcotry

ls /dir/to/list : list directory content (default is .)

-1 : display the content on one column

-l : display the content with long listing format

-a : display the content of the directory (including hidden files)

-R : Display the content of the directory and the content of subdirectories

mv /path/to/file /path/where/to/move : move or rename a file or a directory

cp /path/to/file /path/where/to/copy : copy a file

-r : copy recursively (used to copy directory)

rm /path/to/file : remove a file

-r : remove recursively (used to remove directories)

-f : force remove

mkdir /path/dirName : create an empty directory

rmdir /path/to/dir : remove a directory (works only if the direcotry is empty)

bash redirections

command > file : redirect stdout to file. (creates the file if it doesn't exist and overwrite it if it does exist)

command >> file : redirect stdout to file. (creates the file if it doesn't exist and append to the end it if it does exist)

command 2> file : redirect stderr to file (creates the file if it doesn't exist and overwrite it if it does exist)

command 2>> file : redirect stdout to file. (creates the file if it doesn't exist and append to the end it if it does exist)

command &> file : redirect stdout and stderr to file (creates the file if it doesn't exist and overwrite it if it does exist)

command &>> file : redirect stdout and stderr to file. (creates the file if it doesn't exist and append to the end it if it does exist)

command < file : redirect stdin to file.

command1 | command 2 : uses the output of command1 as the input of command2

file globbing regex

\ : escape character. It deletes the signification of a special character

? : Any character, once.

* : Any character, 0, 1 or many time.

[...] : Any character that is in the class. ex: [abc], [a-z], [0-9]

[^...]: Any character that is not in the class. ex: [^abc], [^a-z], [^0-9]

{s1, s2, sN} : match s1 or s2 or sN

control structure (if)

if <expression>; then

    [statements]

elif <expression>; then

    [statements]

else

    [statements]

fi

control structure (while)

while <expression>; do

    [statements]

done

control structure (for)

for var in <expression>; do

    echo $var

    [statements]

done

control structure (case)

# patterns are file globing regex

case <expression> in

    pattern1)

        [statements]

        ;;

    pattern2)

        [statements]

        ;;

    *)

        [statements]

        ;;

esac

function definition

function functionName {

    [statements]

    [return X]

}

conditional expressions

&& : logical and operator

|| : logical or operator

[[ string ]] : return 0 if string is not empty

[[ -z string ]] : return 0 if the string is empty

[[ string1 == string2 ]] : return 0 if the string are equivalent

[[ string1 != string2 ]] : return 0 if the string are not equivalent

[[ string =~ pattern ]] : return 0 if the string matches the pattern (extended regex)

[[ -e file ]] : return 0 if the file exists

[[ -d file ]] : return 0 if file is a directory

[[ -f file ]] : return 0 if file is a file

[[ -x file ]] : return 0 if file is executable

[[ $n1 -eq $n2 ]] : return 0 if $n1 == $n2

[[ $n1 -lt $n2 ]] : return 0 if $n1 < $n2

[[ $n1 -gt $n2 ]] : return 0 if $n1 > $n2

[[ $n1 -ge $n2 ]] : return 0 if $n1 >= $n2

[[ $n1 -le $n2 ]] : return 0 if $n1 <= $n2

[[ $n1 -ne $n2 ]] : return 0 if $n1 != $n2

more basic bash commands

passwd : change your password

history : consult the history of your command

jobs : list of your pending proccesses

cat file1 file2 ... : concatenate files and print to stdout

more / less file1 file2 .. : diplsay a file page by page on stdout

tail / head number : display the "number" first or last line of a file on stdout

touch file1 file2 ... : change the modification date of the files

chmod : change the privileges of a file / directory

echo "text" : display a line of text to stdout

sort file1 file2 ... : sort the file (combine files if many are specified) and print the result to stdout (files aren't impacted)

-r : sort in reverse order

-n : numerical sort

-u : delete duplicated lines

wc file1 file2 ... : print to stdout the number of characters, words and lines of files

-l : number of lines only

-w : number of words only

-w : number of characters only

diff file1 file1 : compare file1 and file 2 for differences

-i : ignore the character case

-B : ignore empty lines

-w : ignore whitespaces

-c : add context to the output (good for readability)

which commandName : print the path of a command

pushd / popd /path/to/dir : change directory using the directory stack

dirs : print the directory stack

find /path/to/dir -name pattern : find every files and directory that have a name that matches "pattern" in the directory specified and its subdirectories

man commandName : Display the manual for command commandName

sudo command : run the command as superuser

command1 | xargs -i command2 : uses the output of the command1 as the input of the command2. output will be accessible via {} in command2

grep (simple regex)

grep "pattern" file1 file2 ... : print the lines that matched the pattern

-v : print lines that didn't match the pattern

-i : ignore the character case

-l : print the name of the files that have at least one match

-o : print only the piece of line that matched the pattern

-E : uses the extended regex

-q : quiet. returns 0 in $? if at least one line has been matched. 1 if no line matched

variables

VAR=VARVALUE : create a variable VAR. the variable can be accessed like so: $VAR or ${VAR}

VAR="$VAR2" : $VAR will contains the value of $VAR2

VAR='$VAR2' : $VAR will contains $VAR2

VAR=$(command) : $VAR will contains the output of the command

(( VAR = $VAR + 1 )): the double parentheses must be used when doing arithmetics

${VAR#pattern} : return a substring of VAR where the smallest string (starting from the beginning) matching “pattern” will be cut

${VAR##pattern} : return a substring of VAR where the longest string (starting from the beginning) matching “pattern” will be cut

${VAR%pattern} : return a substring of VAR where the smallest string (starting from the end) matching “pattern” will be cut

${VAR%%pattern} : return a substring of VAR where the longest string (starting from the end) matching “pattern” will be cut

$? : the exit status of the last command / function executed. usually 0 when everything went right.

$# : the number of args passed to the script / function

$0 : the name of the script

$n : the nth argument passed to the script / function

$@ : the list of all the argument passde to the script / function

Arrays

myArray=(value1 value2 value3): declare an array

declare -a myArray=(value1 value2 value3): declare an array

${myArray[index]} : access an element (index starts at 0)

myArray[index]= : add or modify the element at index

${#myArray[*]} : return the lenght of the array

${myArray[*]}: all the elements of the array

simple regex

\ : escape character. It deletes the signification of a special character

. : joker. It represents any characters

* : 0, 1 or many repetition of the last character / sequence of character

^ : The beginning of the line

$ : The end of the line

[...] : Any character that is in the class. ex: [abc], [a-z], [0-9]

[^...]: Any character that is not in the class. ex: [^abc], [^a-z], [^0-9]

$...$ : Capture the pattern. The pattern can then be accessed with \1, \2 ... \n depending on the number of capture in the regex

\{n\} : n repetitions of the last character / sequence of character

\{n,\} : At least n repetitions of the last character / sequence of character

\{n, m\} : Between n and m repetitions of the last character / sequence of character

extended regex

\ : escape character. It deletes the signification of a special character

. : joker. It represents any characters

* : 0, 1 or many repetition of the last character / sequence of character

+ : 1 or more repetition of the last character / sequence of character

? : The last character / sequence of character can appear or not

^ : The beginning of the line

$ : The end of the line

[...] : Any character that is in the class. ex: [abc], [a-z], [0-9]

[^...]: Any character that is not in the class. ex: [^abc], [^a-z], [^0-9]

s1|s2 : Either s1 or s2 but not both

(...) : change the priority

{n} : n repetitions of the last character / sequence of character

{n,} : At least n repetitions of the last character / sequence of character

{n, m} : Between n and m repetitions of the last character / sequence of character

sed (simple regex)

sed 'sed script' file : execute the script on every line of "file"

s/pattern/newString/gI : Substitute the piece of the line that matches "pattern" by "newString". g (optional): global, I (optional): ignore case

/pattern/d : delete the line if "pattern" is matched

/pattern/p : print the line if "pattern" is matched

/pattern1/,/pattern2/ : print every lines between the first line that matches "pattern1" to the first line that matches "pattern2"

-i.ext : Modifications done "in-place". A backup file will be created with .ext extension (it is optional)

-n : print only the lines that matched the pattern

awk (extended regex)

awk -Fc 'awk script' file1 file2 ... (where "c" is the delimiter)

typical awk script: 'BEGIN {statements} /pattern/ {script statements} END {statements}'

BEGIN {} : Will be executed once at the start

END {} : Will be executed once at the end

/pattern/ : only lines that matched the pattern will be processed

/pattern1/,/pattern2/ : every line from the first line that matches pattern1 to the first line that matches pattern2 will be processed

{script statements} : core of the script

printf: C-style formatter (man printf)

$n : the nth field of the line

$0 : the entire line

NR : the record number

NF : the number of fields in the record

FS: The field separator (the delimiter)

Created By

gregcheater

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Languages: English

Published: 14th March, 2016
Last Updated: 11th May, 2016
Rated: 5 stars based on 2 ratings

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basic bash commands

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control structure (while)

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more basic bash commands

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variables

simple regex

extended regex

sed (simple regex)

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bash Cheat Sheet by gregcheater

basic bash commands

bash redire­ctions

file globbing regex

control structure (if)

control structure (while)

control structure (for)

control structure (case)

function definition

condit­ional expres­sions

more basic bash commands

grep (simple regex)

variables

simple regex

extended regex

sed (simple regex)

awk (extended regex)

Support Cheatography!

Created By

Metadata

Favourited By

Comments

Add a Comment

Related Cheat Sheets

More Cheat Sheets by gregcheater

Latest Cheat Sheet

Random Cheat Sheet

About Cheatography

Behind the Scenes

Recent Activity

bash redirections

conditional expressions