pager written in perl?

perl5ever has asked for the wisdom of the Perl Monks concerning the following question:

Does anyone know if there is a pager (like 'less' or 'more') written in perl?

I'd like to add customizable syntax highlighting to a pager like 'less'.

I already know about LESSOPEN="| prog %s" and less.vim and ccze. I want to apply custom syntax highlighting to large log files with all of the capabilities of 'less', i.e. up/down line/page, forward and backward regex search, go to line number, go to absolute position offset (+NNNNP), tail mode (+F), etc.

Any ideas? Naturally I'd prefer to write the syntax highlighting logic in perl, but that's not an absolute requirement.

Comment on pager written in perl? Select or Download Code

Replies are listed 'Best First'.
Re: pager written in perl? by MidLifeXis (Monsignor) on Dec 01, 2011 at 19:02 UTC
less syntax highlighting yielded this little goodie as the first hit. --MidLifeXis	[reply]
Re^2: pager written in perl? by perl5ever (Pilgrim) on Dec 01, 2011 at 19:23 UTC
Yes, and I already know about that. The main problem is that, AFAICT, less doesn't support random access of the file when using a LESSOPEN filter. The log files I want to colorize are very large, and it is impractical to colorize the entire file. Also, I want search to be performed on the raw contents, not the colorized version.	[reply]
Re: pager written in perl? by Sewi (Friar) on Dec 01, 2011 at 21:07 UTC
Writing a pager isn't that hard. You might want to use sys* commands to avoid Perl buffering: sysopen your file sysseek to the position Read a fixed length block and look for a line ending Show a line if you find a break, read another block if there is no line ending left Repeat the last two steps until as much lines are shown as you like You may want to save the positions of the last line beginnings using systell to directly sysseek to lines above and below the current screen. Writing a complete less-like pager may be require more features, but a basic one may also do the job if you're only viewing logfiles. I try to use the head and tail Linux commands to limit the number of lines when working with huge logfiles, for example "tail -n 25000 httpd/access.log" to get a day on a medium busy webserver. grep is also good if you're searching for specific information, less and it's coloring will do a good job when viewing the results. Try out Padre - the free Perl IDE and visit my blog's Perl section.	[reply]