How can I run this command in a shell script

Question

This is my shell script but it gives errors:

#!/bin/sh

while getopts "i:o:" flag
do
   case $flag in
   i) file_input=$OPTARG
   ;;
   o) file_output=$OPTARG
   ;;
   esac
done

mplayer -nosound -benchmark -vo yuv4mpeg:file=>(x264 --demuxer y4m \
              --crf 20 --threads auto --output $file_output - ) $file_input

The error message is:

Can't get memory or file handle to write ">(x264 --demuxer y4m --crf 20 --threads auto --output video.264 - )"!FATAL: Cannot initialize video driver.

When I run this cmd on putty:

mplayer -nosound -benchmark -vo yuv4mpeg:file=>(x264 --demuxer y4m \
              --crf 20 --threads auto --output video.264 - ) video.wmv

it works perfectly..

What am I doing wrong?

All solutions are not functionality.. – Sascha Jan 21 '11 at 13:48 — Sascha, Jan 21 '11 at 13:48

score 4 · Answer 1 · answered Jan 21 '11 at 13:35

4

The command you're using uses an intricate bash's pipe stream to subshell syntax, i.e. >() to achieve what you want. Probably your /bin/sh (that you invoke as a shell for this script in shebang) is not the same as the shell you're using interactively (i.e. bash)?

answered Jan 21 '11 at 13:35

GreyCat

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/bin/sh is probably a link to /bin/bash, but under the name /bin/sh, not all the features of bash are available - and the '`=>`' notation in particular is not supported. – Jonathan Leffler Jan 21 '11 at 13:39
@Jonathan: there is no `=>` notation. The `=` is part of the mplayer command. `>(...)` is what Bash parses. – thkala Jan 21 '11 at 13:41
Not always. Nowadays Ubuntu & Debian are popular, and `/bin/sh` is usually implemented with dash there, which is a very minimalistic strictly POSIX-compatible shell. – GreyCat Jan 21 '11 at 13:41
@thkala: You're probably correct - the problems start between the = and the >, and /bin/sh doesn't like it and /bin/bash does. So it is 'process substitution' again...makes sense. – Jonathan Leffler Jan 21 '11 at 13:43

thkala · Answer 2 · 2011-01-21T13:45:20.277

1

The >(...) process substitution operator is Bash-specific. It is also not available if Bash is called as /bin/sh, because in that case Bash restricts itself to a more compliant subset of its features.

Just use #!/bin/bash instead of #!/bin/sh at the start of your script.

edited Jan 21 '11 at 13:45

answered Jan 21 '11 at 13:38

thkala

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score 0 · Answer 3 · answered Jan 21 '11 at 13:37

0

I suggest you to add some ' to protect you special chars:

mplayer -nosound -benchmark -vo 'yuv4mpeg:file=>(x264 --demuxer y4m --crf 20 --threads auto --output $file_output - )' $file_input

answered Jan 21 '11 at 13:37

gabuzo

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How can I run this command in a shell script

3 Answers3