Command line shell for Plan 9 operating system compatible with Linux/Unix.

Originally developed as a practice for the Operating Systems course at Rey JuanCarlos University at Spain, my intention is in the future add more features to become it more Unix-user friendly. Think of it more like ash than like rc.

This code can also be found at https://github.com/piranna/P9sh

Table of Contents Why the name of P9sh? Characteristics Features Optional extensions (for the practice) Requeriments Linux/Unix Plan 9 Built-ins

Why the name of P9sh?

Well, at a first point because it's focused on Plan 9 (althought it compiles under Linux with Plan9port, and maybe i would do a native Linux/Unix version in the future), but also because P9 sound similar to Piranna :-P

Characteristics

• Low size
• Low memory footprint
• Clean and very legible code
• Highly modular
• Full of comments :-D

Features

• Input buffered
• Support for built-ins "a-la" BusyBox
  • cd
• Pipelines
• Stdin & stdout redirection
• Commands in background

Optional extensions (for the practice)

• heredocs (using brackets are identifiers)
• environment vars (set & expansion)
• redirection to environment var

Requeriments

• echo command (needed by heredoc implementation)

Linux/Unix

• Plan9port

Plan 9

• -Nothing- (obviusly... :-D )

Built-ins

A built-in in P9sh is simply a function with a C-main sign, so they are really easy to develop:

1. copy&paste the original source code of the program to embed somewhere in the P9sh source tree (it's own file it's not a bad idea... :-) )
2. rename the built-in main function to something different... and meaningful
3. add an entry for the new built-in at getBuiltin() function
4. ...et voila! :-D