CODEWITHSUNDEEP
shellgnuplot
Jun
Jun

Reputation: 429

Passing Gnuplot variables to a shell expression

I m trying to get the first element of a file within gnuplot:

data = "file.dat"
x = `cat data | head -n 2 | tail -n 1 | awk '{print $1}'`

but this keeps giving me the following error:

no such file or directory

I should write something like x = cat $data | head -n 2 | tail -n 1 | awk '{print $1}'

(with dollar)

Obviouly, this is also not correct.

Any ideas?

Upvotes: 5

Views: 5754

Answers (2)

Christoph
Christoph

Reputation: 48440

Another possiblity instead of the backtics is to use the system function. Then you can build any string and run it as shell expression:

data = 'file.dat'
x = system("head -n 2 ".data." | tail -n 1 | awk '{print $1}'")

Upvotes: 7

Tengis
Tengis

Reputation: 2819

You need to use a 

set macro

and then use the symbol @ to get the value of the variable data (@ in Gnuplot is like $ in bash)

so this should work

x = `cat @data | head -n 2 | tail -n 1 | awk '{print $1}'`

Upvotes: 7

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