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Bash Builder

(C) 2017-2019 Tai Kedzierski, provided under GNU General Public License v3.0.

A toolset for managing bash snippets/libraries, managing in-line documentation, and bundling assets into single executables.

For more on writing cleaner bash scripts, see the clean writing notes.

What is this?

Bash Builder is a tool to help writing bash scripts as multiple files, but collating and distributing as a single file.

Bash, as a language, lacks a usable mechanism to allow developing separate, loosely-related components in separate files, and building libraries of such files for re-use from searchable library paths.

The Bash Builder project aims to provide such a structure:

  • collater for assembling bash scripts using #%include statements
  • customizable search paths for inclusion of files
  • a default library of useful functions to make developing in bash clearer and cleaner
  • a utility to collect and bundle assets and external scripts into a single executable
  • added syntax sugars (e.g. variable names in function signatures)
  • utility to execute bash-builder-augmented scripts

Note that the tools are specifically written against GNU bash and GNU coreutils - strict POSIX sh usage is not supported; run the compatibility check using bash src/ to check that all tools on the system match the required versions.


Clone this repository, run the installation file.

git clone
cd bash-builder

# Optionally, run a compatibility check before installing
bash src/

./ [ --libs ]
# or,
#   sudo ./ [ --libs ]

Then open a new shell, or re-load your ~/.bashrc file.

You can now issue the bbuild command to build your scripts. See the demo folder for an example.

If you installed as root, the commands are installed to /usr/local/bin, otherwise they are installed to ~/.local/bin, and you may need to add that directory to your $PATH



The main collater script that processes the scripts, each into a single executable file.


The source file will be processed for #%include directives, and produce an output file in build-outd/ by default, or in the destination file if specified.

Use the #%include directive in your scripts to import snippets from the builder path $BBPATH, or specify a file to import:

Assuming a folder structure like


You can write this in

# Include some handy message printing functions
#  installed on $BBPATH

#%include std/

# Include a file on a path in the same directory as the specified script

# ... (rest of your script here ) ...

You can run

bbuild bin/

to build your script to the bin/ directory as a executable.

If you have shellcheck installed, you can also have it run against the compiled script.

See bbuild --help for more information.

Extra Syntax !

A syntactic post-processor seeks and replaces macro strings starting with $%. Specify BBSYNTAX=off in your environment to disable this syntax post-processing.

Function signatures

You can declare functions using variable names in the function signature:

$%function copyfrom(host user dest) {
    for srcdir in "$@"; do
        scp "$user@$host:$srcdir" "$dest"

# The first three arguments are assigned to the names ; the rest remain available in "$@"
copyfrom myusername ./downloads /etc/hosts /home/user/backup.log

If fewer arguments than the number named are provided at runtime, the script/subshell will exit, detailing which variable could not be assigned.

Signal traps

You can declare signal traps using a tidy shorthand notation:

# Plain interrupt catchers

$%trap SIGINT SIGTERM int-or-term() {
    echo "Got SIGINT or SIGTERM"

# Declare a trap within an event

do_stuff() {
    touch tmp1 tmp2

    $%trap EXIT regular_exit() {
        # Cleanup
        rm tmp1 tmp2

which will add a trap on the declared signals. While running bash, run trap -l for a list of signals, and help trap for additional bash-specific signals.

Note that trap functions do not take arguments.


An executable that allows you to directly run scripts written for bash builder without a compilation step.

bbrun compiles the script and runs it immediately, and is suitable for a shebang line. The actual runtime script is written to /tmp/, so bbrun provides a $BBRUN_SCRIPT variable to determine the original location of the script.

For example, the following script file can be made executable and run directly:

#!/usr/bin/env bbrun

#%include std/

main() {
    out:info "You ran '$BBRUN_SCRIPT' (compiled to '$0')"

main "$@"


  • This relies on the host having bash-libs installed and accessible to the user.
  • Cannot be used on scripts written to rely on the location of $0 (the running script itself)
    • use the $BBRUN_SCRIPT variable instead, or the std/ lib (version from 2.1.6 onwards)


Processor for a simple, general documentation format that allows you to insert documentation comments in your files, and extract them; documentation comments should be in Markdown - this allows them to simply be printed on-screen, or to file for further transformation into web pages.

The documentation processor is very basic, but has the advantage of being extremely simple and would work on any file that uses a single # to denote comments - it doesn't really care so long as it finds documenmtation comments - the following produces a documentation section named TITLE, and a description. The ### and Usage: tokens are necessary, and the ###/doc terminates the doc comment.

### TITLE Usage:help
# some description

By default, bashdoc will try to find and print any documentation comment tagged as "Usage:bbuild"

Without specifying any arguments, returns all modules along the BBPATH inclusino paths. Example usage:

bashdoc std/

This prints the documentation for the first std/ script found on the $BBPATH path.

Message flags ("tagging")

You can add tag directives to your files using the #%bbtags directive to cause messages to appear when files are included during build. Tags are processed in order of declaration, and use a prefix to determine the message type.

There are 3 tag prefixes:

"i:" -- this causes an info message to be printed
"w:" -- this causes a warning message to be printed
"e:" -- this causes an error message to be printed, and exits the build with failure

Tags without any of these prefixes are only printed when --debug is specified in the arguments.

The following would cause two warning messages to appear during build:

#%bbtags w:deprecated w:use_other

The following would cause a warning message to appear during build, then a failure message and exit.

#%bbtags w:deprecated e:too_dangerous

Default library

The default library is hosted in a separate repository at ; you will be offered a choice to add it during the installation process.

You can configure $BBPATH in your .bashrc file to point to a series of custom locations for scripts, each path is separated by a colon :. By default, BBPATH is automatically set to ~/.local/lib/bash-builder:/usr/local/lib/bash-builder.

A typical use case would be to add your library directory from the current working directory:

export BBPATH="./my-extra-libs:$HOME/.local/lib/bash-builder:/usr/local/lib/bash-builder"

In this case, scripts from the current directory's my-extra-libs/ are loaded preferably, then the user's general library folder, and finally the main library folder is checked.


Autohelp is one of the libraries in bash-libs/libs that is probably worth highlighting:

Autohelp allows you to use documentation comments to produce help.

### TITLE Usage:help
# This is a help section. When using autohelp,
# this text will be printed any time "--help"
# is detected in the arguments!


autohelp:check "$@" # Detect --help string; if found, print help, and exit

When your script subsequently is run with the --help option, autohelp will always kick in, printing the help contents, and exiting.

You can also call the help print routine from within your script using the autohelp:print command (does not cause the script to exit).

See bashdoc std/autohelp/sh for more info.

Debugging Tools is part of the standard libararies, allowing you to print debug-level messages when the debug mode flag is set, as well as providing the ability to view and change variables of a running script using the debug:break function.

See bashdoc std/ for more info

TarSH - Self Extracting and Running TAR files

A utility for collecting various assets into a single self-extracting and running tar file.

Using this, full collections of scripts and binary assets can be deployed in a single runnable file.

See the tarsh documentation and the myip example.


Since Bash Builder is itself written in bash, you could study the tool itself for insight into how it is used.

The primary examples are the bbuild, bbrun, and bashdoc programs themselves written to be compiled by bash builder !

You can see an additional example project in examples/ssh-connection-manager

After installing bash-builder and re-sourcing your .bashrc, you can cd to that directory and run bbuild to build the project.

cd examples/ssh-connection-manager
bin/connect --help

You can also see a simple example of the use of multiple scripting languages combined into one through TarSH in the examples/myip folder

cd examples/myip