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7.4.10 The exit
Statement
The exit
statement causes awk
to immediately stop
executing the current rule and to stop processing input; any remaining input
is ignored. The exit
statement is written as follows:
exit [return code] |
When 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,
as part of executing the exit
statement,
the END
rule is executed
(see section The BEGIN
and END
Special Patterns).
If exit
is used in the body 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.
Any ENDFILE
rules are also skipped; they are not executed.
In such a case,
if you don’t want the END
rule to do its job, set a variable
to nonzero 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
causes awk
to return a “success” status.
In the case where an argument
is supplied to a first exit
statement, and then exit
is
called a second time from an END
rule with no argument,
awk
uses the previously supplied exit value.
(d.c.)
See section gawk
’s Exit Status, for more information.
For example, suppose an error condition occurs that is difficult or
impossible to handle. Conventionally, programs report this by
exiting with a nonzero status. An awk
program can do this
using an exit
statement with a nonzero argument, as shown
in the following 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") } |
NOTE: For full portability, exit values should be between zero and 126, inclusive. Negative values, and values of 127 or greater, may not produce consistent results across different operating systems.
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