function
shell function definition keyword
TLDR
SYNOPSIS
function name() { commands; }
DESCRIPTION
function is a shell keyword for defining reusable command groups. Functions encapsulate commands, accept parameters, and can return exit status values.Functions enable code reuse, modularity, and cleaner scripts. They have local scope for variables with the `local` keyword. Parameters are accessed through positional variables ($1, $2, etc.).In bash, both `function name() { ...; }` and `name() { ...; }` syntax define functions. The POSIX-portable form omits the `function` keyword. In ksh and zsh, the `function` keyword is also supported.
PARAMETERS
NAME
Function name.COMMANDS
Function body commands.$1, $2, etc.
Positional parameters.$@
All parameters.return N
Exit function with status.local VAR
Declare local variable.
CAVEATS
Functions must be defined before use. `return` only sets exit status (0-255), not output values — use command substitution to capture output. Variable scope requires explicit `local` declarations; without it, variables are global.