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linescroll - a tool to monitor log files


linescroll [OPTION] [FILE]...


shows line flow rate in file(s) or stdin.

-c/--combine all input sources into a single source

-l/--limit ITERATIONS exit after ITERATIONS cycles

-s/--speedonly don't print graphs

-p/--print ITERATIONS print only every ITERATIONS'th stats

-f/--filename print filename headings

-a/--noaxislimit do not print the axis limits

-n/--noclear do not clear the screen between prints

-r/--raw treat input lines as values to add to counter

-h/--help print help


linescroll can be used to show how much activity happens in log files or program output.

Bash can be used in conjunction to capture several programs as arguments for linescroll.

stdin can be used as a pipe if no other files are given as arguments, or if the special filename - is used.


Show relative difference of (un-)cached traffic:

linescroll \
<( varnishncsa -F '"%{Varnish:hitmiss}x"' | grep    '"hit"$' ) \
<( varnishncsa -F '"%{Varnish:hitmiss}x"' | grep -v '"hit"$' )

Or just rate of traffic through the cache via stdin:

varnishncsa -F '%h %l %u %t "%r" %s %b "%{Referer}i" "%{User-agent}i" "%{Varnish:hitmiss}x"' \
| linescroll

Build a graph of stats for email:

( printf "From: cache@darkstar\nTo: super@webmasters\nSubject: cache effectiveness snapshot\n\n";
linescroll --limit 60 --print 60 \
    <( varnishncsa -F '"%{Varnish:hitmiss}x"' | grep    '"hit"$' ) \
    <( varnishncsa -F '"%{Varnish:hitmiss}x"' | grep -v '"hit"$' )
) | /usr/sbin/sendmail -fcache super@webmasters


-c, --combine       combine all file source metrics
-l, --limit ITERATIONS
                    stop after number of iterations (default never)
-s, --speedonly     no graph, speed only
-p, --print ITERATIONS
                    print only every Nth iteration
-f, --filename      print filename headings
-h, --help          print usage help
-n, --noclear       do not clear screen between draws
    --nofollow      do not follow file renames
-v, --version       display version number
-r, --raw           input is metric