Last updated: Bash, like any programming language, has some pitfalls that can lead to unexpected errors or behavior. With this will come serious frustrations. Here are ten common Bash pitfalls to watch out for.
Top 10 Bash Pitfalls
1. Unquoted variables
If a variable is not enclosed in quotes, Bash may split it into multiple words, leading to unexpected behavior. Therefore, always use double quotes around variables to ensure they are treated as a single word.
2. Globbing
If you use wildcard characters (such as *, ?, or []) without quoting them, Bash will expand them to match file names in the current directory. This behavior can cause unexpected results if the filenames do not match your intended pattern. Therefore, always quote or escape wildcards to prevent globbing and read my post on
How To Use Bash Wildcards for Globbing.
3. Variable name collisions
Bash has several reserved variable names that should not be used as variable names, such as $PATH and $HOME. Using these names as variable names can cause errors or unexpected behavior.
👉 Learn more about reserved variables names with A Complete Guide To The Bash Environment Variables
4. Exit status of commands
In Bash, a command’s exit status is stored in the special variable $?. If you forget to check the exit status of a command, you may miss errors or unexpected behavior.
5. Overwriting system commands
If you create a Bash function or script with the same name as a system command, your function or script will be called instead of the system command. This can cause unexpected behavior if your function or script has a different behavior than the system command.
👉 Learn how to correctly write bash function with The Complete How To Guide Of Bash Functions
6. Case sensitivity
Bash is case sensitive, meaning that “Foo” and “foo” are treated as different variables or commands. Always be consistent with capitalization to avoid errors.
7. Subshells
Commands executed in subshells (enclosed in parentheses) do not affect the environment of the parent shell. This can cause unexpected behavior if you assume that changes made in a subshell will persist in the parent shell.
👉 Go further and learn How And When To Use The Dot Command In Bash?
8. Aliases
Bash allows you to define command aliases, which can cause confusion or unexpected behavior if the alias has a different behavior than the original command.
9. Use of backticks
Backticks (`) can be used to execute commands and capture their output, but they are deprecated in favor of the $( ) syntax. Using backticks can cause unexpected behavior if the command output contains backticks or other special characters.
10. Line endings
By default, Bash expects Unix-style line endings (LF), not Windows-style line endings (CRLF). Using Windows-style line endings can cause errors or unexpected behavior. This is defined by the Input Field Separator or $IFS variable.
👉 Learn more about The Internal Field Separator Variable: IFS and see concrete example of parsing CSV files in Bash.
Next, you can sharpen your Bash skills further and reduce your troubles by following those 5 Simple Steps On How To Debug A Bash Shell Script. Finally, read my posts on How To Script Error Free Bash If Statement and 5 Mistakes To Avoid For Writing High-Quality Bash Comments.
