frish

A simple command line shell written in the Rust programming language.

Features

Simple syntax of the command line
Builtin commands for basic tasks such as printing the arguments
Builtin commands for working with directories
Builtin commands for working with files
Builtin commands for working with processes
Support for subshells and running commands in the background
Support for redirection of standard input and output
Support for pipelines

Syntax of the command line is as simple as possible: the first word is always the name of a command followed by zero or more arguments. The last three arguments may specify redirection and running of the command in the background and must be in the following order: \<_IN_FILE \>OUT_FILE &.

Install

Install Rust, clone the repo and run cargo run.

Usage

Basic commands

help ... Prints list of builtin commands
name ... Prints the shell name
name word ... Sets the shell name
loglevel ... Print the current logging level
loglevel level... Sets the current loggin level (Error, Info, Debug)
print args ... Print the arguments
echo args ... Print the arguments and final newline character

Directory manipulation

dir.change ... Change the current directory (if no argument given then change to the root directory)
dir.where ... Print the current working directory
dir.make ... Make one or more directories
dir.remove ... Remove one or more directories
dir.list ... List files in the given directory
dir.inspect ... Verbose listing of files in the given directory

File manipulation

link.hard original new ... Create hard link
link.soft original new ... Create soft/symbolic link
link.read links ... Print targets of given links
unlink files ... Remove (unlink) given files
rename source dest ... Rename file
cpcat source dest ... Copy source file to dest (if source or dest is '-' then use standard input or output, respectively)

Process manipulation

pid ... Print PID of the current shell
ppid ... Print PPID of the current shell
lastpid ... Print PID of the last command run in the background
status ... Print status of the last command
exit ... Exit from the current shell
exit status ... Exit from the current shell with the given status
depth ... Print depth of the current subshell
subshell ... Run a subshell with the given command, e.g. subshell echo 42
pipes ... Create a pipeline, e.g., pipes "cat /etc/passwd" "cut -d: -f7" "uniq" "sort" "uniq -c"

Trivia

The original shell specification stems from an assignment in the Operating systems course at Faculity of Computer and Information Science, University of Ljubljana where students must write a command line shell in the C programming language. Hence, we have a simple syntax of the command line and a selected set of commands for file, directory and process manipulation including standard input/output redirection, running commands in the background, and pipeline manipulation.

jurem/frish