moros/doc/shell.md

MOROS Shell

Config

The shell will read /ini/shell.sh during initialization to setup its configuration.

Commands

The main commands have a long name, a one-letter alias, and may have additional common aliases.

Alias command:

> alias d delete

Delete file:

> d a.txt
> del a.txt
> delete a.txt

Copy file:

> c a.txt b.txt
> copy a.txt b.txt

Move file:

> m a.txt b.txt
> move a.txt b.txt

Print string:

> p "Hi"
> print "Hi"

Read file:

> r a.txt
> read a.txt

Write file:

> w a.txt
> write a.txt

Write dir:

> write /usr/alice/ # with a trailing slash to create a dir instead of a file

List files in dir:

> list /usr/alice

When executed without arguments, this command will list the files of the current directory.

Go to dir:

> goto /usr/alice

When executed without arguments, this command will print the current directory.

Combiners (TODO)

The & and | symbols are used only for combiners so there's no needs to double them.

And combiner:

> r a.txt & r b.txt

Or combiners:

> r a.txt | r b.txt

Pipes (TODO)

The pipe symbol | from UNIX is replaced by a thin arrow ->, shortened to >, and the redirection symbol > from UNIX is replaced by a fat arrow => (see below).

Piping the standard output of a program to the write command to emulate a redirection for example would be -> write or > w in short.

An additional standard stream stdnull(3) is added to simplify writing to /dev/null.

Examples:

Read file A and redirect stdout(1) to stdin(0) of write file B:

> r a.txt > w b.txt
> r a.txt 1>0 w b.txt # with explicit streams
> r a.txt -> w b.txt # with thin arrow

Read file A and redirect stderr(2) to stdin(0) of write file B:

> r a.txt 2> w b.txt
> r a.txt 2>0 w b.txt

Suppress errors by redirecting stderr(2) to stdnull(3):

> r a.txt 2>3 w b.txt

Redirect stdout(1) to stdin(0) and stderr(2) to stdnull(3):

> r a.txt > 2>3 w b.txt
> r a.txt 1>0 2>3 w b.txt

Redirections

Redirecting standard IO streams can be done with a fat arrow, for example the output of the print command can be written to a file like so:

> print hello => /tmp/hello

Which is more efficient than doing:

> print hello -> write /tmp/hello

Variables

• Name of the shell or the script: $0
• Script arguments: $1, $2, $3, $4, ...
• Exit code: $?
• Process environment variable: $HOME, ...
• Shell environment variable: $foo, ...

Setting a variable in the shell environment is done with the following command:

> set foo 42

> set bar "Alice and Bob"

And accessing a variable is done with the $ operator:

> print $foo
42

> print "Hello $bar"
Hello Alice and Bob

The process environment is copied to the shell environment when a session is started. By convention a process env var should be in uppercase and a shell env var should be lowercase.

Unsetting a variable is done like this:

> unset foo

Globbing

MOROS Shell support filename expansion or globbing for * and ? wildcard characters, where a pattern given in an argument of a command will be replaced by files matching the pattern.

• * means zero or more chars except /
• ? means any char except /

For example /tmp/*.txt will match any files with the txt extension inside /tmp, and a?c.txt will match a file named abc.txt.

Tilde Expansion

The tilde character ~ is a shortcut to $HOME so ~/test will be expanded to $HOME/test by the shell.