Success
Exit code 0 indicates that a command or script has completed successfully without any errors. It is the universal signal for a successful operation in shell scripting and command-line tools.
- 1The script or command executed as intended and finished its task without encountering any problems.
Any command that completes its job correctly will exit with 0.
#!/bin/bash ls / echo "Exit: $?"
expected output
bin boot dev etc ... Exit: 0
Fix
Always check exit codes after critical commands
WHEN When writing scripts where command failure must be caught and handled.
#!/bin/bash
# Method 1: check $? immediately after the command
some_command
if [ $? -ne 0 ]; then
echo "Command failed" >&2
exit 1
fi
# Method 2: use set -e to exit the script on any non-zero exit code
set -e
some_command # script will abort here if it fails
# Method 3: short-circuit with || for inline handling
some_command || { echo "Command failed" >&2; exit 1; }Why this works
Exit code 0 is the only universally portable indicator of success. Reading $? immediately after a command (before any other command resets it) lets you branch on success or failure. set -e automates this for entire scripts, and the || operator handles it inline.
✕ Assume a command succeeded without checking its exit code
Some commands can fail silently without producing error messages, but will correctly report a non-zero exit code. Always check $? after critical commands.
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