NAME

       pamexec - Execute a shell command on each image in a Netpbm image stream

SYNOPSIS

       pamexec

       ["command"]

       [netpbmfile]

       [-check]

       Minimum unique abbreviation of option is acceptable.  You may use double 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 Standard 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 many 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

       In  addition  to  the options common to all programs based on libnetpbm (most notably -quiet, see  Common
       Options ), pamexec recognizes the following command line option:

       -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

LIMITATIONS

       pamexec 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, which copies the
         first 3 lines of every image (the PPM header) to Standard Output:

           pamexec "cat >/tmp/x; head --lines=3 x" myvideo.ppm

HISTORY

       pamexec was new in Netpbm 10.56 (September 2011).

       Michael Pot wrote it, borrowing from pamsplit.

SEE ALSO

       pamfile(1), pampick(1), pamsplit(1), pnm(1), pam(1), cat man page

DOCUMENT SOURCE

       This  manual  page was generated by the Netpbm tool 'makeman' from HTML source.  The master documentation
       is at

              http://netpbm.sourceforge.net/doc/pamexec.html

netpbm documentation                            21 December 2021                          Pamexec User Manual(1)