AUSAM/doc/man/man1/switch.1

.th SWITCH I 5/31/77
.sh NAME
switch \*- shell multi-way branch command
.sh SYNOPSIS
.bd switch
arg
.br
: label1
.br
	commands...
.br
.bd "	breaksw"
.br
\&. . .
.br
: labeln
.br
	commands...
.br
.bd "	breaksw"
.br
.bd ": default"
.br
	commands...
.br
.bd endsw
.sh DESCRIPTION
.it Switch
searches forward in the input file for the first one of:
.s3
.lp +5 5
1.	a label that pattern-matches
.it arg.
The pattern-matching used is that of the Shell in
generating argument lists.
.lp +5 5
2.	the label
.it default.
.lp +5 5
3.	a matching
.it endsw
command.
.s3
.i0
The Shell resumes reading commands from the next line after the location
where the search stopped.
Thus,
.it switch
supplies a `case' or `computed goto' statement
similar to that of C.
Because `:' is ignored by the Shell, several labels may occur in order,
so that the same sequence of commands is
executed for several different values of
.it arg.
.s3
The
.it breaksw
command searches forward to the next unmatched
.it endsw,
and is normally used at the end of the sequence of commands
following each label.
It may be omitted to allow common code to be shared among label values.
Several
.it breaksw
commands may be written on the same line to exit from that many levels
of nested
.it switch\*-endsw
pairs.
.s3
The optional label
.it default
should be placed last,
since
.it switch
always stops upon discovering it.
The construct can be nested: any labels enclosed by a
.it switch-endsw
pair are ignored by an outer
.it switch.
The most common use of
.it switch
is to process `flag' arguments in a shell procedure.
.sh "SEE ALSO"
if(I), sh(I), while(I)
.sh DIAGNOSTICS
switch: missing endsw
.br
breaksw: missing endsw
.sh BUGS
None of these commands should be hidden behind semicolons.
Nested groups hidden behind
.it if
or
.it else
may also cause trouble.