Know your tools: using inputrc to save keystrokes in the MySQL shell

I do a lot of work with MySQL, and I often bemoan the lack of a concise shortcut to list tables matching a pattern. I much prefer psql's \d shortcut as opposed to mysql's SHOW TABLES. However, since the mysql client uses GNU readline, we can leverage readline's macro facility to make things easier on ourselves!

Readline is the line editor that mysql uses; you can configure it to do many things, but here, I'm going to demonstrate how you can configure it to save you a load of keystrokes.

Readline has a key binding facility, where you can bind a key to a function. For example:

  C-f: forward-word

This binds control-f to the forward-word command, which does exactly what you'd expect. But if you use a double-quote encapsulated string, you can also bind a key to a sequence of keystrokes:

  C-h: "hello"

If you have this in your inputrc, when you type control-h, the string “hello” will be inserted at the cursor. Here's my macro for SHOW TABLES:

  "\C-xs": "show tables like '%%';\e[D\e[D\e[D"

When I hit control-x and then s (a key chord), “show tables like '%%'” appears in my mysql shell, and the cursor is placed between the two '%' characters. (That's what the \e[D characters are; they're the terminal code for moving the cursor left). The quoted string on the left side of the colon is the syntax for defining a key chord.

Since a lot of applications use readline for their line editor, you can do this for many applications, such as Bash. However, let's say you don't want to have this shortcut available in every readline application, or you want different applications to handle the same macro in similar (but different) ways. Inputrc supports conditionals, checking the terminal type or the application in use. So you can make that macro mysql-specific like so:

  $if mysql
    "\C-xs": "show tables like '%%';\e[D\e[D\e[D"

Some programs don't use readline for their line editor; there are other libraries available, such as editline, linenoise, and zle (the line editor within Zsh). Editline supports a macro facility; I believe zle does as well, but I wouldn't count on linenoise supporting it, since its goal is to be minimalistic.

If you want to dig into this some more, there's always the readline documentation. If you're curious what settings, key bindings, and macros I use, here's a my current inputrc file.