8.25. Program: tcteeNot all systems support the classic tee program for splitting output pipes to multiple destinations. This command sends the output from someprog to /tmp/output and to the mail pipe beyond: % someprog | tee /tmp/output | Mail -s "check this" user@host.org This program helps not only users who aren't on Unix systems and don't have a regular tee; it also helps those who are, because it offers features not found on other versions of tee. The four flag arguments are -i to ignore interrupts, -a to append to output files, -u for unbuffered output, and -n to omit copying the output on to standard out. Because this program uses Perl's magic open, you can specify pipes as well as files. % someprog | tctee f1 "|cat -n" f2 ">>f3" That sends the output from someprog to the files f1 and f2, appends it to f3, sends a copy to the program cat -n, and also produces the stream on standard output. The program in Example 8-8 is one of many venerable Perl programs written nearly a decade ago that still runs perfectly well. If written from scratch now, we'd probably use strict, warnings, and ten to thirty thousand lines of modules. But if it ain't broke . . . Example 8-8. tctee#!/usr/bin/perl # tctee - clone that groks process tees # perl3 compatible, or better. while ($ARGV[0] =~ /^-(.+)/ && (shift, ($_ = $1), 1)) { next if /^$/; s/i// && (++$ignore_ints, redo); s/a// && (++$append, redo); s/u// && (++$unbuffer, redo); s/n// && (++$nostdout, redo); die "usage $0 [-aiun] [filenames] ...\n"; } if ($ignore_ints) { for $sig ("INT", "TERM", "HUP", "QUIT") { $SIG{$sig} = "IGNORE"; } } $SIG{"PIPE"} = "PLUMBER"; $mode = $append ? ">>" : ">"; $fh = "FH000"; unless ($nostdout) { %fh = ("STDOUT", "standard output"); # always go to stdout } $| = 1 if $unbuffer; for (@ARGV) { if (!open($fh, (/^[^>|]/ && $mode) . $_)) { warn "$0: cannot open $_: $!\n"; # like sun's; i prefer die $status++; next; } select((select($fh), $| = 1)[0]) if $unbuffer; $fh{$fh++} = $_; } while (<STDIN>) { for $fh (keys %fh) { print $fh $_; } } for $fh (keys %fh) { next if close($fh) || !defined $fh{$fh}; warn "$0: couldnt close $fh{$fh}: $!\n"; $status++; } exit $status; sub PLUMBER { warn "$0: pipe to \"$fh{$fh}\" broke!\n"; $status++; delete $fh{$fh}; } Copyright © 2003 O'Reilly & Associates. All rights reserved. |
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