CODEWITHSUNDEEP
pipeoutputgnuplot
ManuelAtWork
ManuelAtWork

Reputation: 2458

How to direct Gnuplot output into a file descriptor (e.g. pipe) directly?

With Gnuplot it is possible to pipe output into another process, e.g.:

set output "| cat >&2"

This line redirects the plot output into file descriptor "2".

However, in this case all the Output data goes through cat. How can I send the output directly to a file descriptor of my choice?

Upvotes: 2

Views: 1576

Answers (2)

Friedrich -- Слава Україні
Friedrich -- Слава Україні

Reputation: 3764

To avoid cat, you can use

set output '/dev/fd/2'

This requires that the anonymous pipe has been opened before. Since 2 is stderr, this is usually the case. The same holds for /dev/fd/1, which is stdout and seems to be the default, i.e. set output '/dev/fd/1' is the same as set output.

But for /dev/fd/3, the pipe needs to be setup before. E.g. one needs 3>tmp.ps on the command line:

gnuplot -e "set terminal post; set out '/dev/fd/3'; plot sin(x)" 3>tmp.ps

Otherwise it would result in line 0: cannot open file; output not changed system error: No such file or directory. Of course set out 'tmp.ps' would be even more simple.

Upvotes: 1

Christoph
Christoph

Reputation: 48430

You can remove the set output completely from your gnuplot script. Then the output is written to stdout, which you can then redirect:

gnuplot -e "set terminal pngcairo; plot sin(x)" >&2

Upvotes: 2

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