From 958a931dc84212410934b2670bc5cc9ba5185a30 Mon Sep 17 00:00:00 2001
From: koalaman <vidar@vidarholen.net>
Date: Sun, 28 Aug 2016 20:27:25 -0700
Subject: [PATCH] Created SC2181 (markdown)

---
 SC2181.md | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 SC2181.md

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+## Check exit code directly with e.g. 'if mycmd;', not indirectly with $?.
+
+### Problematic code:
+
+```sh
+make mytarget
+if [ $? -ne 0 ]
+then
+  echo "Build failed"
+fi
+```
+
+### Correct code:
+
+```sh
+if ! make mytarget
+then
+  echo "Build failed"
+fi
+```
+### Rationale:
+
+Running a command and then checking its exit status `$?` against 0 is redundant.
+
+Instead of just checking the exit code of a command, it checks the exit code of a command (e.g. `[`) that checks the exit code of a command.
+
+To check that a command returns success, use `if mycommand; then ...`.
+
+To check that a command returns failure, use `if ! mycommand; then ...`.
+
+This also applies to `while`/`until` loops.
+
+### Exceptions:
+
+None.
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