bb/API.md

BB's API

In bb, all interaction (more or less) occurs through binding keypresses (and mouse events) to shell scripts. These shell scripts can perform external actions (like moving files around) or internal actions (like changing the directory bb is displaying). When a shell script runs, bb creates a temporary file, and scripts may write commands to this file to modify bb's internal state.

Helper Functions

• bb: used for modifying bb's internal state (see BB Commands).
• ask: get user input in a standardized and customizable way. The first argument is a variable where the value is stored. The second argument is a prompt. A third optional argument can provide a default value (may be ignored).
• ask1: get a single character of user input. The first argument is a variable where the input will be stored and the second argument is a prompt.
• pause: Display a "press any key to continue" message and wait for a keypress.
• confirm: Display a "Is this okay? [y/N]" prompt and exit with failure if the user does not press 'y'.
• spin: Display a spinning icon while a slow command executes in the background. (e.g. spin sleep 5).

Environment Variables

For startup commands and key bindings, the following values are provided as environment variables:

• $@ (the list of arguments): the full paths of the selected files
• $BBCURSOR: the full path of the file under the cursor
• $BBDOTFILES: "1" if files beginning with "." are visible in bb, otherwise ""
• $BB_DEPTH: the number of bb instances deep (in case you want to run a shell and have that shell print something special in the prompt)
• $BBCMD: a file to which bb commands can be written (used internally)

BB Internal State Commands

In order to modify bb's internal state, you can call bb +cmd, where "cmd" is one of the following commands (or a unique prefix of one):

• .:[01] Whether to show "." in each directory
• ..:[01] Whether to show ".." in each directory
• cd:<path> Navigate to
• columns:<columns> Change which columns are visible, and in what order
• deselect:<filename> Deselect
• dotfiles:[01] Whether dotfiles are visible
• goto:<filename> Move the cursor to (changing directory if needed)
• interleave:[01] Whether or not directories should be interleaved with files in the display
• kill Exit with failure
• move:<num*> Move the cursor a numeric amount
• quit Quit bb
• refresh Refresh the file listing
• scroll:<num*> Scroll the view a numeric amount
• select:<filename> Select
• sort:([+-]method)+ Set sorting method (+: normal, -: reverse), additional methods act as tiebreaker
• spread:<num*> Spread the selection state at the cursor
• suspend Suspend bb (SIGSTP signal)
• toggle:<filename> Toggle the selection status of

For any of these commands (e.g. +select), an empty parameter followed by additional arguments (e.g. bb +select: <file1> <file2> ...) is equivalent to repeating the command with each argument (e.g. bb +select:<file1> +select:<file2> ...).

Note: for numeric-based commands (like scroll), the number can be either an absolute value or a relative value (starting with + or -), and/or a percent (ending with %). Scrolling and moving, % means percent of screen height, and %n means percent of number of files (e.g. +50% means half a screen height down, and 100%n means the last file)

Final Notes

Internally, bb writes the commands (NUL terminated) to a file whose path is in$BBCMD and reads from that file when bb resumes. These commands can also be passed to bb at startup, and will run immediately. E.g. bb '+col:n' '+sort:+r' . will launch bb only showing the name column, randomly sorted.

bb also optimizes any scripts that only contain just a bb command and no shell variables, other commands, etc. (e.g. bb +move:+1) These bb-command-only scripts directly modify bb's internal state without spawning a shell, so they're much faster and avoid flickering the screen.