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Sed does not make changes in the file but to the standard output
04-06-2009
#!/usr/bin/env bash
# @(#) s1 Demonstrate sponge.
echo
set +o nounset
LC_ALL=C ; LANG=C ; export LC_ALL LANG
echo "Environment: LC_ALL = $LC_ALL, LANG = $LANG"
echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version "=o" $(_eat $0 $1) perl
set -o nounset
echo
FILE=${1-data1}
SPONGE=./sponge
cp original-data $FILE
echo " Data file $FILE:"
cat $FILE
echo
echo " Results for default STDOUT:"
cat $FILE | $SPONGE
cp original-data $FILE
echo
echo " Results for re-writing $FILE:"
sed '/2/d' $FILE | $SPONGE $FILE
cat $FILE
exit 0% ./s1 Environment: LC_ALL = C, LANG = C (Versions displayed with local utility "version") OS, ker|rel, machine: Linux, 2.6.11-x1, i686 Distribution : Xandros Desktop 3.0.3 Business GNU bash 2.05b.0 perl 5.8.4 Data file data1: 1 2 3 Results for default STDOUT: 1 2 3 Results for re-writing data1: 1 3
#!/usr/bin/perl
# @(#) sponge Read STDIN, write to file at EOF.
## Modification history: when / who / what: most recent at top.
# Relocate to end if grows too long, or re-sequence.
#
# 2009.04.06 / drl / original.
use warnings;
use strict;
my ($debug);
$debug = 1;
$debug = 0;
my ( $buf, $file, $tmp, $temporary );
$file = shift || ">-";
$temporary = "/tmp/sponge_$$";
open( $tmp, ">", $temporary ) || die " Cannot open $temporary for write.\n";
print " debug write - temporary is :$temporary:\n" if $debug;
while ( read( STDIN, $buf, 16384 ) ) {
print $tmp $buf;
}
close $tmp;
open( $tmp, "<", $temporary ) || die " Cannot open $temporary for read.\n";
print " debug read - temporary is :$temporary:\n" if $debug;
if ( $file eq "-" ) {
open( FILE, ">-" ) || die " Cannot open STDOUT for writing.\n" if $debug;
}
else {
open( FILE, ">$file" ) || die " Cannot open $file for write.\n";
}
print " debug write - file is :$file:\n" if $debug;
while ( read( $tmp, $buf, 16384 ) ) {
print FILE $buf;
}
unlink $temporary;
exit(0);
... cheers, drl|
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