CyprSH

A minimalistic POSIX-compliant shell written in C from scratch to deepen my understanding of systems programming.

Features

• Lexer with full POSIX token recognition
• Recursive descent parser
• Interactive mode with readline history
• Script mode

Building

make          # release build
make debug    # debug build with sanitizers

Usage

./cyprsh              # interactive mode

Status

Work in progress. Currently implemented:

• Lexer
• Parser
• Executor (partially, only external commands)
• Pipelines
• Redirections
• Word expansion
• Builtins
• Job control

Examples

cyprSH> echo "Hello world"
Hello world

cyprSH> ls -la | wc -l
14

cyprSH> echo first > test.txt
cyprSH> echo second >> test.txt
cyprSH> cat test.txt
first
second

cyprSH> date; whoami; pwd
Thu Jun  4 07:14:15 PM CEST 2026
luptakk
/home/luptakk

cyprSH> echo a && echo b
a
b

cyprSH> false || echo "fallback"
fallback

License

GPL v3