66 lines
1.2 KiB
Markdown
66 lines
1.2 KiB
Markdown
---
|
|
tags:
|
|
- shell
|
|
---
|
|
|
|
# Functions in Bash
|
|
|
|
We don't name function parameters in the function declaration. Instead we have
|
|
an implied index of arguments: `$1, $2, $3,...`. When the function is called,
|
|
the first value after the function name becomes `$1` by default, then the
|
|
subsequent arguments.
|
|
|
|
```bash
|
|
function expandRange() {
|
|
declare -a expandedRange=()
|
|
for (( i=$1; i<=$2; i++ )); do
|
|
expandedRange+=($i)
|
|
done
|
|
echo "${expandedRange[@]}"
|
|
}
|
|
```
|
|
|
|
```bash
|
|
expandedRange=$(expandRange 1 4)
|
|
echo $expandedRange
|
|
# 1 2 3 4
|
|
```
|
|
|
|
## Get all arguments as an array
|
|
|
|
We can access all the arguments passed to a function using the `$@` syntax we
|
|
encountered before when
|
|
[passing arguments to scripts](Passing_arguments_to_Bash_scripts.md).
|
|
(Here a function is a kind of script in miniature so the process is the same.)
|
|
|
|
```sh
|
|
function numberThings() {
|
|
i=1
|
|
for f in "$@"; do
|
|
echo $i: "$f"
|
|
(( i++ ))
|
|
done
|
|
}
|
|
```
|
|
|
|
## Local variables
|
|
|
|
```sh
|
|
var1="I'm variable 1"
|
|
|
|
function myfunction() {
|
|
var2="I'm variable 2"
|
|
local var3="I'm variable 3"
|
|
}
|
|
|
|
myfunction
|
|
echo $var1
|
|
echo $var2
|
|
echo $var3
|
|
|
|
# I'm variable 1
|
|
# I'm variable 2
|
|
```
|
|
|
|
> The convention is to put functions at the top of the script, after the shebang
|
|
> and after the global variables
|