unshell

a minimal shell. concise syntax, very little bloat while staying extensible

tour: how unshell differs from POSIX shells

• tab-indented or brace-delimited control blocks (if/elif/else/for/foreach)

   # no : needed. it's more concise than python that's right
   if true
   	pwd
   	date
   	echo this is a branch
   elif [ -d /tmp/ ] { echo not true } # or use braces if you'd like
   elif false {
   	# multiline
   }
   else
   	sudo poweroff

• atomic arguments by default: $var expands to exactly one argument (no implicit splitting or globbing)

   # creates "./my file.txt", not ./my and ./file.txt
   var="my file.txt"
   touch $var

• explicit re-tokenization with ...: opt into POSIX-like splitting by re-parsing a string

   # runs `seq 5 | tac`, not `seq 5 "| tac"` or `seq 5 "|" "tac"`
   ending="| tac"
   seq 5 ...$ending

• square-brackets as a shorthand for subshells

   # equivalent to echo $(pwd). [] is much faster to type than $()
   echo [seq 10 | tail -1]
   	# => 10
  
   # all of these will be one argument, not expanding by default
   # unless you use ...[] or ...$() etc
  
   echo "[pwd]" # [] are literals when inside quotes, to avoid collision
   	# => [pwd]
   echo "$(pwd) $[pwd]" # $() and $[] are still subshells inside quotes
   	# => /tmp /tmp
   echo '$(pwd)' # everything is literal inside single quotes
   	# => $(pwd)

• stream-based, line-based foreach. like xargs except not cancer to use

   # idk if this should be the default, just add it to your config
   # if you like it
   alias each foreach
  
   # indent-based block
   seq 5 | each i
   	touch $i.txt
   	echo [date +%s] "done text file creation for index $i"
  
   # use braces if you want to chain further
   ls | each file { du -h $file } | sort -h

• arbitrary shorthand string handling, using your userspace handlers

   cd /tmp/
   touch foo1.txt foo2.txt foo3.txt
  
   # prints a literal foo*.txt. you have no handler by default
   echo foo*.txt
  
   # enable the shipped extension handler. easy to modify or replace
   set expansions.handler util/expansion_handler.py
  
   # intercept tokens containing *, outside of strings
   set expansions.characters "*" on
  
   # prints foo1.txt foo2.txt foo3.txt, as 3 separate arguments
   # expansion_handler.py received "foo*.txt"
   # and returned a JSON array ["foo1.txt", "foo2.txt", "foo3.txt"]
   echo foo*.txt
  
   # you can easily make your own handler for syntax like
   # fu@3 -> "fufufu", or anything else you want
   # Gemini 3's ideas: s3://bucket/* and pkg@latest

more info: full spec

repl details: repl guide

install

deps: Rust, Python (optional; for the default config), fzf (optional; for better repl tab completion)

git clone https://github.com/veilm/unshell
./unshell/install.sh

if for some reason you don't need interactive usage and want to skip the (patched) rustyline compilation, you can install unshell without the repl:

./unshell/install.sh --no-repl

usage

ush                 # repl
ush path/to/script  # run a script file line-by-line
ush --norc          # skip startup files
ush --rc path       # source only this init file

support

open a GitHub issue or ping me on twitter. I'd be happy to answer any possible question, or discuss Unix or shells in general

license

MIT