execline
Software
skarnet.org

The case program

case compares a value against a series of regular expressions, and executes into a program depending on the first expression the value matches.

Interface

In an execlineb script:

     case [ -E | -e | -i | -n ] value
     {
       [ regex { prog... } ]
       [ regex { prog... } ]
       ...
     }
     progdefault...

• case reads an argument value and a sequence of directives in a block.
• Each directive is a regular expression followed by a block.
• case matches value against the regular expressions in the order they are given.
• As soon as value matches a regex, case executes into the prog... command line that immediately follows the matched regex.
• If value matches no regex, case eventually execs into progdefault....

Options

• -e : Interpret the regex words as basic regular expressions.
• -E : Interpret the regex words as extended regular expressions. This is the default.
• -i : Perform case-insensitive matches.
• -n : Do not transmit the matching expression and subexpressions to prog... via the environment. This is the default.
• -N : Make the matching expression and subexpressions available to prog's environment.

Subexpression matching

If the -N option has been given, and value matches a regex, then case will run prog with a modified environment:

• The 0 variable will contain the regex that value matched.
• The # variable will contain the number of subexpressions in regex.
• For every integer i between 1 and the number of subexpressions (included), the variable i contains the part of value that matched the ith subexpression in regex.

To retrieve that information into your command line in an execline script, you can use the elgetpositionals program.