Builtin Commands

fortsh includes 58 builtin commands. Builtins are executed directly by the shell without spawning external processes.

Quick Reference

Navigation & Directories

Command	Description	Source
cd	Change directory	`builtins.f90:builtin_cd`
pwd	Print working directory	`builtins.f90:builtin_pwd`
pushd	Push directory onto stack	`directory_builtin.f90`
popd	Pop directory from stack	`directory_builtin.f90`
dirs	Show directory stack	`directory_builtin.f90`
prevd	Previous directory (fish-style)	`builtins.f90`
nextd	Next directory (fish-style)	`builtins.f90`
dirh	Directory history	`builtins.f90`

Variables & Environment

Command	Description	Source
export	Export variables	`builtins.f90:builtin_export`
unset	Unset variables	`builtins.f90:builtin_unset`
readonly	Mark variables readonly	`builtins.f90:builtin_readonly`
declare	Declare variables	`builtins.f90:builtin_declare`
local	Function-local variables	`builtins.f90:builtin_local`
printenv	Print environment	`builtins.f90:builtin_printenv`
shift	Shift positional params	`builtins.f90:builtin_shift`

I/O & Output

Command	Description	Source
echo	Print text	`builtins.f90:builtin_echo`
printf	Formatted output	`printf_builtin.f90`
read	Read input	`read_builtin.f90`

Job Control

Command	Description	Source
jobs	List jobs	`builtins.f90:builtin_jobs`
fg / bg	Foreground/background job	`builtins.f90:builtin_fg`
kill	Send signal	`builtins.f90:builtin_kill`
wait	Wait for jobs	`builtins.f90:builtin_wait`
coproc	Coprocess	`builtins.f90:builtin_coproc`

Scripting & Control

Command	Description	Source
exit	Exit shell	`builtins.f90:builtin_exit`
source / .	Execute file	`builtins.f90:builtin_source`
eval	Evaluate string	`eval_builtin.f90`
exec	Replace shell	`builtins.f90:builtin_exec`
return	Return from function	`builtins.f90:builtin_return`
break	Break from loop	`builtins.f90:builtin_break`
continue	Continue loop	`builtins.f90:builtin_continue`

Command Identification

Command	Description	Source
type	Show command type	`command_builtin.f90`
which	Find command	`command_builtin.f90`
command	Execute bypassing functions	`command_builtin.f90`
hash	Command cache	`builtins.f90:builtin_hash`

Testing & Conditionals

Command	Description	Source
test / [	Test expression	`test_builtin.f90`
[[	Advanced test	`advanced_test.f90`
getopts	Parse options	`getopts_builtin.f90`

Aliases & Abbreviations

Command	Description	Source
alias / unalias	Define/remove alias	`builtins.f90:builtin_alias`
abbr	Abbreviations (fish-style)	`builtins.f90:builtin_abbr`

History & Completion

Command	Description	Source
history	Command history	`builtins.f90:builtin_history`
fc	Edit history	`builtins.f90:builtin_fc`
complete	Define completions	`builtins.f90:builtin_complete`
compgen	Generate completions	`builtins.f90:builtin_compgen`

Shell Options

Command	Description	Source
set	Set options	`shell_options.f90`
shopt	Shell options	`shell_options.f90`
config	Configuration	`builtins.f90:builtin_config`

Signals

Command	Description	Source
trap	Set signal handlers	`builtins.f90:builtin_trap`

System & Debugging

Command	Description	Source
umask	File creation mask	`builtins.f90:builtin_umask`
ulimit	Resource limits	`builtins.f90:builtin_ulimit`
times	Process times	`builtins.f90:builtin_times`
let	Arithmetic evaluation	`builtins.f90:builtin_let`
perf	Performance metrics	`builtins.f90:builtin_perf`
memory	Memory statistics	`builtins.f90:builtin_memory`

Special

Command	Description
:	Null command (no-op)
help	Display help

Implementation Notes

All builtins are implemented in Fortran and execute within the shell process. Source files are located in:

src/execution/builtins.f90 - Core builtins
src/scripting/*.f90 - Specialized builtins (printf, read, test, etc.)

Return values follow POSIX conventions:

0 - Success
1 - General failure
2 - Usage/syntax error
127 - Command not found (for exec, source)