ULOS Manual Pages - bsh(1) | Back

NAME
  bsh - Better Shell

SYNOPSIS
  bsh -l|--login
  bsh

DESCRIPTION
  bsh is a Bourne-like shell.  It is a significantly improved, and in fact rewritten, version of the sh shell shipped with ULOS prior to Release 1.7.  It supports piping, input/output redirection, command aliases, basic glob expansion, and substitution.

  bsh is prioritized over lsh(1) by the sh(1) utility, if it is installed.  lsh is still available, and may be set as a user's default shell with the passwd(1) utility.

SYNTAX
  This section contains explanations of the syntax of bsh.  It should be familiar to those familiar with the Bourne shell.

  Environment Variable Substitution
  Environment variables may be subsituted with the ${VARIABLE_NAME} syntax for variables whose names contain characters outside of the [0-9a-zA-z_] range, and $VARIABLE_NAME for those variables whose names do not contain such characters.  For example, the variable foo-bar must be substituted with ${foo-bar}, whereas the variable baz may be substituted with $baz.

  Command Aliases
  Aliases may be defined with the alias builtin;  see BUILTINS below.

  Glob Expansion
  Globs with the * character are supported in place of a filename, or the end of a filename at the end of a path specifier, or in place of a directory name anywhere else.  Thus, the following cases are valid:

    /bin/*
    /lib/*/test
    /tmp/part*

  The following case is not valid and will result in undefined behavior:

    /example/part*/foo

  Piping
  bsh supports piping the output of program foo into the input of program bar with the following syntax:
    
    foo | bar

  These chains may be extended indefinitely.

  I/O Redirection
  A program foo's input may be directed to an arbitrary file f, where replacing the single > with a double >> will append to the file f rather than overwriting it.

    foo > f

  Similarly, a program bar's output may be pointed to a file f with the < operator:

    bar < f

  Comments
  Comments extend from the first # found in a line to the end of that line.

  Command Chains
  bsh supports the && operator for conditional program execution.  Combined with input/output redirection and piping (see the corresponding sections above) this can be quite powerful.  Program invocations may be separated with a ;, as such:

    foo; bar a b c; baz

SHELL BUILTINS
  bsh contains a small set of built-in commands.  It will only create a process for a builtin command if that command's input or output is being redirected.

  The following is a short description of each builtin command:

    builtins
      Print each available built-in command.

    cd
      Change the current working directory.  If no argument is given, changes to $HOME;  if the argument given is -, changes to $OLDPWD.

    set
      If no arguments are provided, prints the value of all environment variables.  Otherwise, for each argument matching key=value, sets the environment variable key's value to value.
      
    unset
      Unsets each provided environment variable.

    alias
      If no arguments are provided, prints all aliases specified in the current shell.  Otherwise, for each argument, if that argument matches key=value, aliases key to value;  otherwise, if the argument is a valid alias, prints it and its value.

    unalias
      Unsets each provided alias.

    kill
      Kills processes.  Valid options are: sighup, sigint, sigquit, sigpipe, sigstop, sigcont, or otherwise any signal defined by the process(3) library.

    exit
      Exits the current bsh session.  The shell's exit status is 0 or, if present, the first argument converted to a number.

    logout
      Exits a login shell.

    pwd
      Prints the current working directory (i.e. the value of $PWD).

    true
      Exits with a status of 0.

    false
      Exits with a status of 1.

    time
      Executes the provided command and prints the amount of time it took to execute.

    source FILE
      Evaluate the provided FILE line-by-line with the current shell environment.

COPYRIGHT
  Better Shell copyright (c) 2021 Ocawesome101 under the DSLv2.

REPORTING BUGS
  Please report bugs at https://github.com/ocawesome101/oc-ulos/issues.