A perl program that acts similar to "tail" in unix.
Just provide the name of the file, an optional
number of lines, and an optional characters per line.
#!/usr/bin/perl
## PerlTail
## Does a "tail" of a file using seek.
use strict;
my $bigfile = shift or die "Usage: $0 filename <lines> <linesize>\n";
my $linesback = shift || 10; ## How many "lines" back to read
my $charsperline = shift || 80; ## A rough guess
open(BIG, $bigfile) or die "Could not open $bigfile: $!\n";
## Make a reasonable guess as to how far back to go.
my $gobackchars = $linesback*$charsperline+1;
## Figure out how big it is
my $filesize = -s $bigfile;
## We do not want to go back *too* far:
$gobackchars = $filesize if $gobackchars > $filesize;
seek(BIG,-$gobackchars,2);
## We probably arrived in the middle of a line,
## so throw out everything to the start of a new line
<BIG>;
## Now we print out the rest of the lines:
print while(<BIG>);
close(BIG);
Update: There is noting wrong with
any of the programs/modules already out there. This is
just a *snippet*, a quick little piece of code I wrote
that demonstrates a good use of seek. Sheesh! :)
In reply to Perltail
by turnstep
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