45 lines
954 B
Markdown
45 lines
954 B
Markdown
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---
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tags: [shell]
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created: Saturday, February 22, 2025
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---
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# Capturing program error in Bash
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If you want to capture possible error immediately after running the command, use
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`!`:
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```sh
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if ! grep "pattern" file.txt; then
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echo "Pattern not found"
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fi
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```
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If you want to store the outcome of a command and refer to it later, use `$?`.
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This built-in variable captures the exit status of the last executed command (0
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for success, non-zero for failure):
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```sh
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ls -a
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status=$? # Store immediately if needed later
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if [ $status -ne 0 ]; then
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# handle the error case
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else
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# command was successful (exit code = 0)
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fi
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```
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Note: `$?` will be overwritten by any command that runs after the one you're
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interested in. If you need to check multiple commands' statuses, store $?
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immediately after each command:
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```sh
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command1
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status1=$?
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command2
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status2=$?
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if [ $status1 -ne 0 ] || [ $status2 -ne 0 ]; then
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echo "One of the commands failed"
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fi
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```
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