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Aliases
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10.9 Shell Functions

sh_init
The C shell has aliases (10.2 ) . But until System V Release 2, the Bourne Shell had almost (10.10 ) no way for users to set up their own built-in commands. Functions are like aliases, but better. For instance, functions can return a status (44.7 ) and have much more reasonable syntax (10.7 ) . bash and the Korn Shell have shell functions, too. To find out all about functions, check a shell programming book. There are examples in the sh_init file on the CD-ROM. Here are the examples from articles 10.2 and 10.3 changed into Bourne shell aliases:
  • The la function includes "hidden" files in ls listings. The lf function labels the names as directories, executable files, and so on:

    la () { ls -a "$@"; }
    lf () { ls -F "$@"; }

    The spaces and the semicolon (; ) are both important! [3] The "$@" (44.15 ) is replaced by the command-line arguments (other options, or directory and filenames), if you use any:

    [3] A function is a Bourne shell list construct (13.8 ) . You can omit the semicolon in bash -but, if you do, your functions won't be portable.

    $ la -l somedir
    
                ...runs 
    ls -a -l somedir

  • This next simple function, cur , gives the name of your current directory and then lists it:

    cur()
    {
        pwd
        ls
    }

That example shows how to write a function with more than one line. In that style, with the ending curly brace on its own line, you don't need a semicolon after the last command.

- JP


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