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Full Discussion: [solved] awk: placement of user-defined functions
Top Forums Shell Programming and Scripting [solved] awk: placement of user-defined functions Post 302774175 by alister on Friday 1st of March 2013 10:41:06 AM
Old 03-01-2013
Quote:
Originally Posted by zaxxon
Hi folks,

is there any recommendation, especially from a point of performance, about where to place a user-defined function in awk, like in BEGIN{} or if it is only need once at the end in END{}? Or doesn't it matter at all since, awk is so clever and only interprets it once, wherever it is placed?
With regard to performance of user-defined functions, placement does not matter to the only implementation with whose internals I'm a bit familiar, nawk.

The only way to improve performance of a given user-defined function is to change implementation. Typically, gawk is by far the slowest of all. nawk is noticeably faster. mawk is much faster still. Typically. You'd have to benchmark your program to confirm.

With regard to placement of the function definition, it's not allowed to be inside BEGIN or END. It should be at the same top-level as patterns and actions. If your implementation allows you to embed it, be aware that others may not.

Regards,
Alister
These 2 Users Gave Thanks to alister For This Post:
MadeInGermany zaxxon
 

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LEARN ABOUT SUNOS

ucblinks

ucblinks(1B)					     SunOS/BSD Compatibility Package Commands					      ucblinks(1B)

NAME

       ucblinks - adds /dev entries to give SunOS 4.x compatible names to SunOS 5.x devices

SYNOPSIS

       /usr/ucb/ucblinks [-e rulebase] [-r rootdir]

DESCRIPTION

       ucblinks  creates symbolic links under the /dev directory for devices whose SunOS 5.x names differ from their SunOS 4.x names. Where possi-
       ble, these symbolic links point to the device's SunOS 5.x name rather than to the actual /devices entry.

       ucblinks does not remove unneeded compatibility links; these must be removed by hand.

       ucblinks should be called each time the system is reconfiguration-booted, after any new SunOS 5.x links that are needed have been  created,
       since the reconfiguration may have resulted in more compatibility names being needed.

       In  releases prior to SunOS 5.4, ucblinks used a  nawk rule-base to construct the SunOS 4.x compatible names. ucblinks no longer uses  nawk
       for the default operation, although  nawk rule-bases can still be specifed with the -e option.  The  nawk rule-base equivalent to the SunOS
       5.4 default operation can be found in /usr/ucblib/ucblinks.awk.

OPTIONS

       -e rulebase     Specify rulebase as the file containing nawk(1) pattern-action statements.

       -r rootdir      Specify rootdir as the directory under which dev and devices will be found, rather than the standard root directory /.

FILES

       /usr/ucblib/ucblinks.awk        sample rule-base for compatibility links

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWscpu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       devlinks(1M), disks(1M), ports(1M), tapes(1M), attributes(5)

SunOS 5.10							    13 Apr 1994 						      ucblinks(1B)
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