exit Statement
The exit statement causes awk to immediately stop
executing the current rule and to stop processing input; any remaining input
is ignored. It looks like this:
exit [return code]
If an exit statement is executed from a BEGIN rule the
program stops processing everything immediately. No input records are
read. However, if an END rule is present, it is executed
(see section The BEGIN and END Special Patterns).
If exit is used as part of an END rule, it causes
the program to stop immediately.
An exit statement that is not part
of a BEGIN or END rule stops the execution of any further
automatic rules for the current record, skips reading any remaining input
records, and executes
the END rule if there is one.
If you do not want the END rule to do its job in this case, you
can set a variable to non-zero before the exit statement, and check
that variable in the END rule.
See section Assertions,
for an example that does this.
If an argument is supplied to exit, its value is used as the exit
status code for the awk process. If no argument is supplied,
exit returns status zero (success). In the case where an argument
is supplied to a first exit statement, and then exit is
called a second time with no argument, the previously supplied exit value
is used (d.c.).
For example, let's say you've discovered an error condition you really
don't know how to handle. Conventionally, programs report this by
exiting with a non-zero status. Your awk program can do this
using an exit statement with a non-zero argument. Here is an
example:
BEGIN {
if (("date" | getline date_now) < 0) {
print "Can't get system date" > "/dev/stderr"
exit 1
}
print "current date is", date_now
close("date")
}
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