Pamexec User Manual(0) Pamexec User Manual(0)NAMEpamexec - Execute a shell command on each image in a Netpbm image
stream
SYNOPSISpamexec
['command']
[netpbmfile]
[-check]
Minimum unique abbreviation of option is acceptable. You may use dou‐
ble hyphens instead of single hyphen to denote options. You may use
white space in place of the equals sign to separate an option name from
its value.
DESCRIPTION
This program is part of Netpbm(1)pamexec reads a Netpbm image stream as input. For each image, it runs
a specified shell command and supplies the image to it as Standard
Input (with a pipe).
netpbmfile is the file name of the input file, or - to indicate Stan‐
dard Input. The default is Standard Input.
Many Netpbm programs understand multimage Netpbm streams themselves, so
you don't need to use pamexec to run the program on the images in the
stream. Ideally, all Netpbm programs would have that capability, but
multi-image streams are a relatively recent invention, so older Netpbm
programs just process the first image in the stream and then stop.
Even recently written Netpbm programs work that way, since the authors
aren't aware of the multi-image possibility.
Another way to process a multi-image stream is to use pamsplit to
explode it into multiple files, one image per file. You can then
process those files.
To run your command on a subset of the images in the stream, use
pampick to select the desired images from the input stream and pipe the
result to pamexec.
OPTIONS-check This causes pamexec to exit without processing any further
images if the command has a nonzero exit status.
APPLICATIONS
To make an animated GIF movie:
pamexec pamtogif myvideo.ppm | gifsicle --multifile >myvideo.gif
LIMITATIONSpamexec assumes all commands consume all of Standard Input. If yours
doesn't (perhaps it just exits when it's seen enough), you can buffer
through a temporary file like this:
pamexec 'cat >/tmp/x; head -3 x' myvideo.ppm
HISTORYpamexec was new in Netpbm 10.56 (September 2011).
Michael Pot wrote it, borrowing from pamsplit.
SEE ALSOpamfile(1) , pampick(1) , pampick(1) , pnm(1) , pam(1) , cat man page
netpbm documentation 11 August 2011 Pamexec User Manual(0)
