Curly brace

Multipurpose shell syntax. More information: https://www.gnu.org/software/bash/manual/bash.html#index-hash.

• Isolate variable names:

echo ${HOME}work

• Brace expand sequences:

echo {1..3} {a..c}{dir1,dir2,dir3}

• Check if variable is set before returning text:

echo ${variable:+variable is set and contains $variable}

• Set default values in case variable is unset:

echo ${variable:-default}

• Return variable length in characters:

echo ${#variable}

• Return a string slice:

echo ${variable:3:7}

• Recursively expand a variable:

echo ${!variable}

• Capitalize all the characters:

echo ${variable^^}