A.54 library(shell): Elementary shell commands

This library provides some basic (POSIX) shell commands defined in Prolog, such as pwd and ls for situations where there is no shell available or the shell output cannot be captured. Note that in recent versions (since 10.1.13) the GUI frontend swipl-win can capture process output on all supported platforms.

shell

Execute an interactive shell. Uses shell_command/1 to find a suitable shell.

The shell's exit status is not our business, so shell/0 succeeds whatever it is. Note that if the shell cannot be executed shell/2 raises an exception.

shell_command(-Shell:atom)

True when Shell is the preferred executable for running an interactive shell. Used by shell/0. The following options are tried to find a suitable shell command:

1. The Prolog flag shell
2. The environment variable %comspec% (Windows only)
3. The environment variable $SHELL
4. The Prolog flag posix_shell

Errors

existence_error(config, shell) if no suitable shell can be found.

cd

cd(Dir)

Change working directory

pushd

pushd(+Dir)

popd

dirs

Manage the directory stack:

• pushd/1 is as cd/1, pushing th old directory on a stack
• pushd/0 swaps the current directory with the top of the stack
• popd/0 pops to the top of the stack
• dirs/0 lists the current directory and the stack.

pwd

Print current working directory

ls

ls(+Pattern)

Listing similar to Unix ls -F, flagging directories with /. If the terminal supports it, Prolog source files are rendered as links using the OSC 8 escape sequence. When using Epilog, clicking a Prolog file opens it in the editor.

[det]mv(+From, +To)

Move (Rename) a file. If To is a directory, From is moved into the directory. Uses expand_file_name/2 on the From argument.

[det]rm(+File)

Remove (unlink) a file

[det,multifile]file_style(++File, =Style)

True when File should be listed as a terminal hyperlink. The default only links Prolog source files.

Style

is either url to make a hyperlink or a valid style argument for ansi_format/3.

cls

CLear Screen. Emits ANSI control characters to clear the terminal.