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