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From: ampbox@gmail.com
Newsgroups: comp.graphics.apps.gnuplot
Subject: How to know total number of blocks in a file?
Date: Thu, 15 Mar 2012 07:43:43 -0700 (PDT)
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Hi all,

I have a data file with multiple data blocks (groups of data lines separated by blank lines). I want to plot only the last block. 

I can do it like 

      plot 'filename' every :::<blockNO>::<blockNO> 

where <blockNO> is the block number, and since it is the last block, this number equals the total number of blocks in my data file.

The problem is, I don't know how many blocks are there in my data file. (Because my simulation adds a new block every few hours and the longer simulation runs, the more number of frames (block) I get.)

Is there a built-in variable like GPVAL_DATA_X_MAX etc. to give me this information? 

Another possible solution: can I get the number of lines etc. by a bash command (I am in Linux) INSIDE my gnuplot script and give it to a variable? I mean something like:

NBLOCKS = `!wc -l filename`

Thanks in advance,
Masoud.