Functions vs. scripts (Bash)

How to not confuse functions with scripts when programming in Bash?

The problem

While programming in Bash, I often make calls to functions within the same file (e.g., backup_site, or to external scripts (e.g. source update_site.sh). Usually, external sites have an extention .sh, so it's easy to see that they are external files. But I don't do this always. In both cases, it's important that global variables (if that's the correct name) are preserved. How to keep track of whether someting is a function or an external script?

What would happen if a name is used by both?

How to keep track

Consistent Naming Conventions

• Use a prefix for functions, e.g., fn_backup_site, fn_update_db
• Use a .sh extension for external scripts, e.g., update_site.sh
• Keep external scripts in a dedicated directory, e.g., scripts/

List Defined Functions

• Use declare -F to check if a function exists:
• To list all functions in the current session: declare -F

Check if a Name is an External Script

• Use type to determine whether something is a function, alias, or external command:type backup_site

Explicitly Source External Scripts

Several ways to force the use of an external script:

• source ./backup_site.sh
• Include path. E.g.: ./backup_site.sh
• bash backup_site.sh
• Use command. E.g.: command backup_site.

Functions take precedence

If a function and an external script share the same name (e.g., backup_site), the function will be executed - not the file.