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102 lines
1.4 KiB
Markdown
102 lines
1.4 KiB
Markdown
# Runtime Arguments
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Pass data into your script at execution. Arguments follow the script name:
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```bash
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./your_script.sh first_argument
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```
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Inside the script, `$1` references the first argument, `$2` the second, and so on.
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Let's see this in `arguments.sh`:
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```bash
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touch arguments.sh
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```
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Open `arguments.sh` and add:
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```bash
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#!/usr/bin/env bash
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echo "Arg 1: $1"
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echo "Arg 2: $2"
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echo "Arg 3: $3"
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```
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Save and exit. Make it executable:
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```bash
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chmod +x arguments.sh
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```
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Run with three arguments:
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```bash
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./arguments.sh dog cat bird
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```
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Output:
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```bash
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Arg 1: dog
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Arg 2: cat
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Arg 3: bird
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```
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To access *all* arguments, use `$@`. Update `arguments.sh`:
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```bash
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#!/usr/bin/env bash
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echo "All arguments: $@"
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```
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Save. Run again with arguments:
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```bash
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./arguments.sh dog cat bird
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```
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Output:
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```bash
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All arguments: dog cat bird
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```
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### Script Name (`$0`)
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`$0` references the script itself. This is useful for logging or unique operations.
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You can even use `$0` for self-deletion. **Handle with extreme caution!**
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Create `self_destruct.sh`:
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```bash
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touch self_destruct.sh
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```
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Open `self_destruct.sh` and add:
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```bash
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#!/usr/bin/env bash
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echo "This script: $0 is self-destructing."
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rm -f $0
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```
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Save and exit. Make it executable:
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```bash
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chmod +x self_destruct.sh
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```
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Run it:
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```bash
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./self_destruct.sh
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```
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The script will print its name, then delete itself. **This is irreversible. No second chances.** Always back up before testing self-deletion.
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