exsh is the PSCAL shell front end: an interactive and scripting POSIX-ish shell that parses shell source into the shared PSCAL AST, which the shared bytecode compiler lowers and the PSCAL VM runs.

exsh carries no VM or code generator of its own — it builds against pscal-core, pulled in automatically via CMake FetchContent. A few shared shell pieces (the backend shell runtime and the shared AST/builtin helpers) live in pscal-core and are compiled from there.

exsh's in-process cross-front-end integration (driving Pascal / CLike / Rea) and its smallclue/SDL features are mobile/iOS-gated and are not part of this standalone host build.

cmake -S . -B build      # fetches and builds pscal-core, then exsh
cmake --build build -j
./build/exsh script.sh

The binary lands at build/exsh. Run it interactively with no arguments, pass a script path to run it, or use -c 'command' to run an inline command.

cmake --install build --prefix /usr/local

This puts the exsh binary in <prefix>/bin, the example scripts in <prefix>/share/exsh/examples, and the shell docs (plus this README) in <prefix>/share/doc/exsh. The fetched pscal-core dependency contributes its own install rules as well, so a full install also lays down its static library, headers, and docs.

The manifest-driven regression corpus lives in tests/ and runs under CTest against the binary you just built:

ctest --test-dir build --output-on-failure

You can also run the harness directly. It picks up the binary from EXSH_BIN (falling back to build/exsh), which is how the umbrella build exercises the same corpus:

EXSH_BIN=./build/exsh tests/run.sh            # all tests
EXSH_BIN=./build/exsh tests/run.sh --only printf   # a subset by id substring
tests/run.sh --list                            # list available cases

The harness treats exit code 77 as a skip. A few cases drive a sibling component's example programs (CLike hello / simple_web_server) that a standalone exsh clone does not ship; those self-skip so a minimal build stays green, while a full checkout that has them runs them for real.

Runnable scripts live in examples/exsh/, covering builtins, conditionals, pipelines, redirection, functions, and threading demos:

./build/exsh examples/exsh/pipeline
./build/exsh examples/exsh/functions

Shell documentation is in docs/:

• exsh_overview.md: the shell overview and feature guide
• exsh_bash_builtin_coverage.txt: bash builtin coverage matrix