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← Revision 5 as of 2023-01-29 21:18:51 ⇥
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| Arguments passed to a function implicitly overwrite the positional variables (`$1`, `$2`, and so on) as well as the argument count variable (`$#`). All of these will be reset to the original values upon the function's return. | Arguments passed to a function implicitly overwrite the [[Bash/Variables#Positional_Variables|positional variables]] as well as the [[Bash/Variables#Special_Variables|argument count variable]] (`$#`). All of these will be reset to the original values upon the function's return. |
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=== Local Scope === To mark a variable as belonging only to a function's scope, declare it with the `local` [[Bash/BuiltinCommands#Local|builtin]]. {{{ local x=y }}} |
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if isdirectory "$some_directory"; then : fi |
Bash Function
Declaration
A function is declared with one of:
myfunction() {
:
}
function myfunction() {
:
}If the function keyword is used, the parentheses are optional.
Usage
The above functions would be called like:
myfunction "first argument" "second argument"
Arguments
Arguments passed to a function implicitly overwrite the positional variables as well as the argument count variable ($#). All of these will be reset to the original values upon the function's return.
Note that $0 is not overwritten.
Local Scope
To mark a variable as belonging only to a function's scope, declare it with the local builtin.
local x=y
Error and Return Codes
By default a function does not set the exit code. But it also does not clear the code. The final command in a function effectively sets the error code for the function as well.
The return builtin causes the function to return immediately with a specified exit code.
isdirectory() {
if [ -d "$1" ]; then
return 0
else
return 1
fi
}
if isdirectory "$some_directory"; then
:
fi