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 is bundled with some helper scripts for performing common tasks. These scripts are installed to /etc/bb/, which is added to bb's $PATH environment variable at runtime. ~/.config/bb/ is also added to the $PATH with higher priority, so you can override any of these scripts by putting your own version there.

• bbstartup: The script run when bb first launches. It calls bbkeys by default and sets up some configuration settings like which columns to display.
• bbkeys: The script called by bb to create all of bb's key bindings. It's currently very hacky, but it amounts to a bunch of calls to bbcmd bind:<key>:<script>
• bbshutdown: The script run when bb exits. The default implementation saves the current configuration settings to ~/.local/share/bb/settings.sh, which is run by bbstartup to restore the settings at launch.
• bbask [-1] [prompt [initial]]: Get user input in a standardized and customizable way and output it to STDOUT.
• bbcmd <cmd>*: Modifybb's internal state (see BB Commands).
• bbconfirm [prompt]: Display a "Is this okay? [y/N]" prompt and exit with failure if the user does not press 'y'.
• bbpause: Display a "press any key to continue" message and wait for a keypress.
• bbpick [prompt]: Select one of NULL-delimited multiple inputs and print it.
• bbunscroll: Print text to the screen above the cursor instead of below it.

Environment Variables

When bb runs scripts, following values are provided as environment variables:

• $@ (the list of arguments): the full paths of the selected files
• $BB: the full path of the file under the cursor
• $BBDEPTH: 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)
• $BBGLOB: the glob pattern bb is using to determine which files to show

BB Internal State Commands

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

• bind:<keys>:<script> Bind the given key presses to run the given script
• cd:<path> Navigate to
• columns:<columns> Change which columns are visible, and in what order
• deselect[:<filename>] Deselect (default: all selected files)
• fg[:num] Send a background process to the foreground (default: most recent process)
• glob:<glob pattern> The glob pattern for which files to show (default: *)
• goto:<filename> Move the cursor to (changing directory if needed)
• help Show the help menu
• interleave[:01] Whether or not directories should be interleaved with files in the display (default: toggle)
• 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 (default: all visible files)
• sort:([+-]method)+ Set sorting method (+: normal, -: reverse, default: toggle), additional methods act as tiebreaker
• spread:<num*> Spread the selection state at the cursor
• toggle[:<filename>] Toggle the selection status of (default: all visible files)

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

Globbing

bb uses glob patterns to determine which files are visible. By default, the pattern is *, which means all files except those starting with a . (dot). bb's globs are POSIX-compliant and do not support bash-style extensions like ** for recursive matches. bb supports multiple, space-separated globs, so for example, you can display all files including dotfiles with the glob: .* * (by default, pressing the . key will toggle this behavior). The current bb glob is available in $BBGLOB, which can be used in scripts if left unquoted.

Final Notes

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

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