.Dd November 9, 2022
.Dt SH 1
.Os
.Sh NAME
.Nm sh
.Nd shell command interpreter
.Sh SYNOPSIS
.Nm sh
.Op Fl ceils
.Op Ar script Oo argument ... Oc
.Nm sortix-sh
.Op Fl ceils
.Op Ar script Oo argument ... Oc
.Sh DESCRIPTION
.Nm
is the command line interpreter for the shell language.
It reads and executes commands from the standard input or the
.Ar script
file if specified.
.Nm
is interactive if the standard input is a terminal and no
.Ar script
file was specified.
.Pp
The standard shell
.Nm sortix-sh
is currently primitive and cannot execute most scripts.
.Nm sh
is currently a thin wrapper that detects non-interactive use and invokes a
better shell instead, named in the
.Ev SORTIX_SH_BACKEND
environment variable if set, or named in
.Xr proper-sh 5
if it exists, and otherwise
.Xr dash 1
is invoked.
.Pp
The options can be unset by prefixing them with a plus
.Sq +
instead of a dash
.Sq - .
.Pp
The options are as follows:
.Bl -tag -width "12345678"
.It Fl c
The
.Ar script
argument contains the script's text instead of a path to the script file.
.It Fl e
Exit if any command exit non-zero.
.It Fl i
Interactively read and execute commands.
.It Fl l
The shell is a login shell.
Interactive shells run the
.Xr profile 5
script on startup instead of the
.Xr shrc
script.
This option is set if the shell is invoked by a name starting with a dash
.Sq - .
.It Fl s
Read commands from the standard input (the default).
This option can be combined with the
.Fl c
option to execute the script text in the
.Ar script
argument before reading normally from the standard input
.El
.Sh ENVIRONMENT
.Nm
uses environment these variables:
.Bl -tag -width "HISTFILE"
.It Ev ENV
File to execute on non-login interactive startup instead of
.Pa ~/.shrc
per
.Xr shrc 5 .
This variable is subject to path expansion.
.It Ev HISTFILE
Save the shell history in this file.
The default is
.Pa ~/.sh_history .
.It Ev HISTSIZE
Maximum number of commands in the saved shell history.
The default is 500.
.It Ev HOME
The user's home directory
.Sq ( ~ ) .
.It Ev PATH
The colon-separated list of directory paths to search for programs.
.It Ev PWD
Set to the current working directory.
.It Ev SHELL
Set to
.Nm .
.It Ev SHLVL
Depth of recursive shell sessions.
The outermost interactive shell (depth 1) will currently refuse to exit on an
end-of-file condition (^D) when on the
.Pa /dev/tty1
terminal to avoid accidentally powering off the machine.
.It Ev SORTIX_SH_BACKEND
Name of a better shell to use for non-interactive use per
.Xr proper-sh 5 .
This variable takes precedence over
.Pa /etc/proper-sh .
.El
.Sh FILES
.Bl -tag -width "/etc/proper-sh" -compact
.It Pa ~/.profile , /etc/profile , /etc/default/profile
.Xr profile 5
script whose commands are run on non-login interactive shell startup.
.It Pa /etc/proper-sh
Name of a better shell to use for non-interactive use per
.Xr proper-sh 5 .
The
.Ev SORTIX_SH_BACKEND
environment variable takes precedence over this file if set.
.Xr dash 1
is used by default if it is installed.
.It Pa ~/.sh_history
The saved shell history.
This location is controlled by the
.Ev HISTFILE
environment variable.
.It Pa ~/.shrc , /etc/shrc , /etc/default/shrc
.Xr shrc 5
script whose commands are run on login interactive shell startup.
The
.Ev ENV
environment variable overrides the search for the script if set.
.El
.Sh EXIT STATUS
.Nm
exits with the same exit status as the last run command, or 0 if no command has
been run.
.Sh SEE ALSO
.Xr dash 1 ,
.Xr profile 5 ,
.Xr proper-sh 5 ,
.Xr session 5 ,
.Xr shrc 5 ,
.Xr login 8