This project is under active development and still considered work in progress.

What is errand?

Errand is simple task runner that serves as an alternative to GNU Make. But instead of using it as a build system Errand should only be used for running tasks where simple build systems can be part of a task.

Some facts about the project

• By default shells are pure so if you would want to have access to lets say .bashrc you would need to source it inside of a task. This way the task don't rely on personal settings and therefor are more likely to be reproducible on other machines.
• All of the contents of a task gets ran in one shell so you don't need \ like you do in Make. You can also reuse outputs of previous lines. The tasks are behaving more like a shell script.
• By default all environmental variables do not get passed to Errand but you can enable this by setting @env on at the beginning of the Errandfile.

How this all works?

1. In your project folder create file Errandfile and put the following code in it. Be default erd expects Errandfile to be there. You can override which file will be used by -f flag (erd -f otherfile).

2. Then run erd command in this folder. Just like with make.

   @env on
   
   @task demo "A job doing something"
     # Shell commands are executed in the current directory
     ls -l
     pwd
   end

3. If no arguments were provided erd will display list of all available tasks in the Errandfile.

4. If you want to run a specific task then run erd demo and this will execute appropriate task. You can also chain tasks with erd demo othertask etc. The program will follow order of you arguments and try to execute all tasks.

Tested with

• glibc GCC 12 (gcc)
• glibc Clang 11 (clang)
• glibc TinyCC 2022-07-15 (tcc)
• musl GCC 12 (musl-gcc)
• musl Clang 11 (musl-clang)

Compilation

Clone the repository and do make. This will use the default compiler provided with $CC.

You can also provide additional flags to C compiler with EXTRA_FLAGS variable. For static compilation this would looks like make EXTRA_FLAGS=-static. If you want to include debug symbols you could do it with EXTRA_FLAGS=-static -ggdb. You get the gist.

Here are couple of examples.

# Dynamic compilation with gcc
make clean && CC=gcc make

# Static compilation with clang
make clean && CC=clang make EXTRA_FLAGS=-static

# Static compilation with gcc
make clean && CC=gcc make EXTRA_FLAGS=-static

# Static compilation with musl clang
make clean && CC=musl-clang make EXTRA_FLAGS=-static

# Dynamic compilation with tinycc
make clean && CC=tcc make

Alternatively you can use Nix shell which already provides three compilers (GCC, Clang, TinyCC). To invoke the shell do nix-shell.

Caveats & recommendations

Syntax highlighting

You can use Ruby language for syntax highlighting.

Multi-line expressions are currently not provided.

Instead of this:

for ((i=1; i<=10; i++))
do
  echo $i
done

Do the following instead:

for i in {1..10}; do echo $i; done

Or make an external script and call it with bash script.sh.

Features, ideas & todo's

Implemented

• Override default shell with @shell /bin/bash operation. For the first version this should be in global scope.

Would want to have

• Parallel execution (similar to make -jN). This should be provided with a flag erd -p and should automatically detect number tasks user wants to execute and then execute those tasks in parallel with pthreads.
• Read environmental variables and toggle that option with @env [on/off].
• Check for existence of commands on a machine with @assure gcc valgrind where this will execute command -v [cmd] to check for existence of the program on a local machine.
• Allow creating of environmental variables in the global scope with @var SOMEVAR "somevalue". These variable should be passed to all tasks and if @env on then these variables should override existing ones or be appended to the list.

License

erd was written by Mitja Felicijan and is released under the BSD two-clause license, see the LICENSE file for more information.