I recently figured out how to write a shell function. The problem is that pretty quickly I’d forgotten which functions I’d written, or fi I had a general name, I couldn’t remember what they did exactly.

So, I wanted to figure out a few things:

1. Figure out which functions are defined
2. Figure out where a single function is defined
3. Figure out what the function definition is

This is where using Print and Whence came in handy.

What Are Available Functions?

We can use the print built-in: print -loc ${(ok)functions} (note, l is new line separated, o is ascending ordering, and c makes columns).

Where Is The Function Defined?

Figuring out where a function is defined can be done with whence -v [function]. This is useful if you want to modify a function definition.

What Is The Function Definition?

Before going in and changing a function definition, however, you may want to know what the function actually does. The whence builtin is one way to accomplish this with the -c and the -f options.

According to the manual:

• the c option prints “the results in acsh-like format. This takes precedence over-v.”
• The f option “causes the contents of a shell function to be displayed, which would otherwise not happen unless the -c flag were used.”

The commands would look like whence -c [function] or whence -f [function].

It’s worth noting that the Stackoverflow conversation on the topic notes several other approaches, however, whence performed accomplished my use case nicely and I didn’t feel the need to explore much further at this time.