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# pm-jarandf.rc -- pick (rand)om line from (f)ile
#
# File id
#
# Copyright (C) 1997-2010 Jari Aalto
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 2 of the
# License, or (at your option) any later version
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details at
# <http://www.gnu.org/copyleft/gpl.html>.
#
# Description
#
# Return random line or a line from a file. This subroutine uses
# shell command `awk' and possibly `wc' to be as small burden to the
# system as possible.
#
# Required settings
#
# You must have awk that supports VAR=value assignment syntax outside
# the code block: that is, in the input line. I know no awk that
# would not have this feature, but at least you know now what it takes.
#
# % awk '{print VAR; exit;}' VAR=1 /etc/passwd
#
# Try using GNU awk, if your standard awk didn't print 1 in above
# test. (Put this line to the top of your .procmailrc)
#
# AWK = "gawk"
#
# Call arguments (variables to set before calling)
#
# If intend to call this subroutine many times, then please calculate
# the number of lines beforehand and pass it to this subroutine. If
# the MAX is not set, then `wc' is called every time to find your the
# line count.
#
# o FILE, from what file to select. Make sure this exists; existence
# is not checked here.
# o [MAX] optional, number of lines in the FILE.
#
# Returned value
#
# variable LINE
#
# Example usage
#
# # Select random line from a file
#
# $RC_RANDF = $PMSRC/pm-jarand.rc
# $COOKIE = $HOME/txt/cookie.lst
#
# ...somewhere..
# MAX=20 FILE=$COOKIE INCLUDERC=$RC_RANDF
#
# # LINE contains randomly read line
#
# Change Log: (none)
# ............................................................ &init ...
id = "pm-jarandf.rc"
dummy = "
========================================================================
$id: init:
"
# ........................................................... &input ...
# FILE; MAX; defined by user
# ..................................................... &output-vars ...
# output variables
LINE
# ........................................................... &do-it ...
# Prevent calling sh -c here. Speeds up procmail.
jarandfShellmetas = $SHELLMETAS
SHELLMETAS
:0
* FILE ?? [a-z]
{
# If max is not set beforehand
:0
* ! MAX ?? ^^[0-9]+^^
{
# Awk can't know how many lines are in the file in advance,
# we must find it out.
MAX = `wc -l $FILE`
}
# It works like this:
# - When line number(NR) is 1, calculate random line
# - calculated line is same as current line number, print and exit.
LINE = `$AWK \
' \
function GetRand(i, j) \
{ \
srand(); \
return (i + int ( rand()*j )); \
} \
{ \
if ( NR == 1 ) { line = GetRand(1, max); } \
if ( NR == line ) { print; exit; } \
} \
' max=$MAX $FILE `
}
SHELLMETAS = $jarandfShellmetas
dummy = "$id: end:"
# pm-store.rc ends here
|
