Bash is a powerful scripting language that is used by many developers. This cheat sheet is a collection of Bash tips and tricks that will help you write better Bash scripts.
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| Command |
Description |
echo |
Print a message to the console |
printf |
Print a formatted message to the console |
cat |
Print the contents of a file to the console |
pwd |
Print the current working directory |
cd |
Change the current working directory |
ls |
List the contents of a directory |
mkdir |
Create a new directory |
touch |
Create a new file |
cp |
Copy a file or directory |
mv |
Move a file or directory |
rm |
Remove a file or directory |
find |
Find files or directories |
grep |
Search for a string in a file |
wc |
Count the number of lines, words, and characters in a file |
sort |
Sort the lines in a file |
uniq |
Remove duplicate lines in a file |
head |
Print the first 10 lines of a file |
tail |
Print the last 10 lines of a file |
man |
Display the manual page for a command |
which |
Display the location of a command |
type |
Display the type of a command |
alias |
Create an alias for a command |
history |
Display the command history |
clear |
Clear the console |
exit |
Exit the console |
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| Command |
Description |
var="value" |
Assign a value to a variable |
echo $var |
Print the value of a variable |
echo ${var} |
Print the value of a variable |
echo "$var" |
Print the value of a variable |
echo "${var}" |
Print the value of a variable |
echo '$var' |
Print the literal value of a variable |
echo '${var}' |
Print the literal value of a variable |
echo "${var:-default}" |
Print the value of a variable or a default value if the variable is not set |
echo "${var:=default}" |
Assign a default value to a variable if the variable is not set |
echo "${var:?error}" |
Print an error message if the variable is not set |
echo "${var:+value}" |
Print a value if the variable is set |
echo "${var:offset}" |
Print a substring of a variable |
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| Command |
Description |
function_name() { ... } |
Define a function |
function_name() { echo "Hello World"; } |
Define a function |
function_name() { echo "Hello $1"; } |
Define a function with parameters |
function_name() { echo "Hello $@"; } |
Define a function with parameters |
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| Command |
Description |
array=(value1 value2 value3) |
Define an array |
echo ${array[0]} |
Print the value of an array element |
echo ${array[@]} |
Print the values of an array |
echo ${#array[@]} |
Print the number of elements in an array |
echo ${#array[0]} |
Print the length of an array element |
array[0]="value" |
Assign a value to an array element |
array+=(value) |
Append a value to an array |
unset array[0] |
Remove an array element |
unset array |
Remove an array |
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| Command |
Description |
if [ condition ]; then ... fi |
If statement |
if [ condition ]; then ... else ... fi |
If/else statement |
if [ condition1 ]; then ... elif [ condition2 ]; then ... else ... fi |
If/elif/else statement |
case value in pattern1) ... ;; pattern2) ... ;; esac |
Case statement |
case value in pattern1) ... ;; pattern2) ... ;; *) ... ;; esac |
Case statement with a default case |
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| Command |
Description |
for var in value1 value2 value3; do ... done |
For loop |
for var in $(command); do ... done |
For loop |
for (( i=0; i<10; i++ )); do ... done |
For loop |
while [ condition ]; do ... done |
While loop |
until [ condition ]; do ... done |
Until loop |
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| Command |
Description |
read var |
Read input from the console |
read -p "Enter a value: " var |
Read input from the console with a prompt |
read -a array |
Read input from the console into an array |
read -d |
Read input from the console until a delimiter is found |
read -s |
Read input from the console without echoing the input |
read -n |
Read a specified number of characters from the console |
read -t |
Read input from the console with a timeout |
echo "Hello World" > file.txt |
Redirect output to a file |
echo "Hello World" >> file.txt |
Append output to a file |
echo "Hello World" 2> file.txt |
Redirect error output to a file |
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| Command |
Description |
set -x |
Enable debugging |
set +x |
Disable debugging |
set -v |
Print shell input lines as they are read |
set +v |
Do not print shell input lines as they are read |
set -n |
Read commands but do not execute them |
set +n |
Execute commands read from the command line |
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| Command |
Description |
echo "Hello World" |
Print a string |
echo -n "Hello World" |
Print a string without a newline |
echo -e "Hello\tWorld" |
Print a string with escaped characters |
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| Command |
Description |
. |
Execute a script in the current shell |
source |
Execute a script in the current shell |
: |
Do nothing |
true |
Do nothing |
false |
Do nothing |
break |
Exit a loop |
continue |
Skip to the next iteration of a loop |
return |
Exit a function |
exit |
Exit the shell |
set |
Set shell options |
unset |
Unset shell options |
export |
Export a variable |
readonly |
Make a variable read-only |
declare |
Declare a variable |
typeset |
Declare a variable |
local |
Declare a local variable |
eval |
Evaluate a string as a command |
exec |
Execute a command |
shift |
Shift positional parameters |
wait |
Wait for a background process to complete |
pwd |
Print the current working directory |
cd |
Change the current working directory |
pushd |
Push the current working directory onto the directory stack |
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| Command |
Description |
set -o |
List shell options |
set -o noclobber |
Do not overwrite existing files |
set -o errexit |
Exit on error |
set -o errtrace |
Exit on error in a function |
set -o nounset |
Exit on unset variable |
set -o pipefail |
Exit on pipe failure |
set -o xtrace |
Print commands and their arguments as they are executed |
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| Command |
Description |
alias |
List aliases |
alias name="command" |
Create an alias |
unalias |
Remove an alias |
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| Command |
Description |
function name { ... } |
Define a function |
name() { ... } |
Define a function |
declare -f |
List functions |
declare -f name |
List a function |
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| Command |
Description |
array=(value1 value2 value3) |
Create an array |
array[0]="value" |
Assign a value to an array element |
array+=(value) |
Append a value to an array |
unset array[0] |
Remove an array element |
unset array |
Remove an array |
declare -a |
List arrays |
declare -a array |
List an array |
declare -p |
List variables |
declare -p array |
List a variable |
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| Command | Description |
| -------------------------------- | ------------ | -------------- | ------------ |
| [[ condition ]] | If statement |
| [[ condition1 && condition2 ]] | If statement |
| [[ condition1 | | condition2 ]] | If statement |
| [[ ! condition ]] | If statement |
| [[ value1 == value2 ]] | If statement |
| [[ value1 != value2 ]] | If statement |
| [[ value1 < value2 ]] | If statement |
| [[ value1 > value2 ]] | If statement |
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| Command |
Description |
for var in "${array[@]}"; do ... done |
For loop |
for (( i=0; i<10; i++ )); do ... done |
For loop |
while [[ condition ]]; do ... done |
While loop |
until [[ condition ]]; do ... done |
Until loop |
select var in "${array[@]}"; do ... done |
Select loop |
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| Command |
Description |
read -p "Enter a value: " value |
Read input from the console |
read -p "Enter a value: " -s value |
Read input from the console without echoing the input |
read -p "Enter a value: " -n 5 value |
Read a specified number of characters from the console |
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