thus is a custom Unix shell for POSIX platforms.
- Job control (
fg,bg,&,^Z) - Pipelines
- File redirection (
<file,2>&1, etc.) - Globbing (
*,?,[...]) - Quotes (
'...', "...") - Variables (
set,unset,$VAR$, etc.) - Aliasing (
alias,unalias) - Configuration files (
~.thuslogin,~.thusrc) - Cached history (
~.thushistory) - Automated integration of built-in commands
thus uses cbs as its build system.
> git clone --recursive https://trenthuber.com/git/thus.git
> cd thus/
> cc -o build build.c
> buildAfter building, you can use install to add the shell to your path. The default
installation prefix is /usr/local/, but a custom one can be passed as an
argument to the utility.
> sudo ./installAfter installing, you can use uninstall to remove the shell from the install
location.
> sudo ./uninstallWhile thus operates for the most part like Bourne shell, there are a few places where it takes a subtly different approach.
Most other shells by default will execute all the commands in a line regardless
of the previous one's exit status. Typically, in order to control whether a
command runs based on the exit status of the last, these shells provide list
operators like && and ||. Neither of the these operators are included in
this shell. Instead, the && operator is the default behavior between commands,
while the || operator is forgone entirely. If any command fails, the whole
string of commands fail whether from a script or from an interactive session.
Like other shells, variables, tildes, and escape sequences will be expanded
inside of double quotes, but not single quotes. Unlike other shells however,
quotes do not concatenate with other arguments that are not separated from the
quote by whitespace. For example, the command echo "foo"bar would print
foo bar whereas other shells would print foobar.
Variables are referred to by strings of characters that begin and end with a
$. For example, evaluating the path variable would look like $PATH$. Setting
variables is done with the set built-in command, not with a name=value
syntax. This syntax is similarly avoided when declaring aliases with the alias
built-in command.
Additionally, all shell variables are automatically made to be environment
variables, so there's no need to export variables.
Prepending ./ to executables located in the current directory is not mandatory
unless there already exists an executable in $PATH$ with the same name that
you would like to override.
The $HOME$, $PWD$, and $PATH$ variables are always initialized with
trailing slashes. Therefore, whenever one of these variables or ~ is
substituted in the shell, it will retain the trailing slash.
If there is whitespace between a file redirection operator and a filename
following it, then it is not parsed as a file redirection, but instead as two
separate arguments. Something like ls >file would redirect the output of the
ls command to file, whereas ls > file would list any files that might be
named > or file.