uSH: a small shell

Written by Noah Brecht

Pronounced micro-shell!

A micro-shell for the Linux OS. It supports I/O piping and has a few builtins. It is considerably smaller that bash, zsh, etc. It also has no dependencies, making it extremely portable.

Build Process

The build process is extremely simple:

Clean the source tree:
make clean

Compile uSH:
make

Install:
sudo make install

Dependencies

Required

• make
• gcc
• ld (provided with gcc)
• strip

Optional

• gdb (for debugging the shell)
• valgrind (for finding memory leaks)

The Makefile installs uSH as /bin/ush by default. Change the value of $INSTALLDIR and $INSTBIN to change that location.

Syntax

Run a single command:
:? <command> <arguments>
Pipe multiple commands together:
:? <command1> <arg1> | <command2> <arg2>
Run a system command with the same name as a builtin command:
:? <command>^ <arguments>
Variables can be used on the command line:
:? $I_Am_A_Command $I_Am_An_Argument
Variables can be assigned on the command line:
:? $var = value

Command-Line Options

--version: Print shell version information
--help: Print shell help text
--buffer <val>: Set the buffer size of the shell
--script <file>: Execute commands from a script