NAME

       mdm.screen - run a command under mdm-master

SYNOPSIS

       mdm.screen [-c iospec] [-n slaves] command

DESCRIPTION

       mdm.screen runs command under mdm-master so that mdm-run commands in command can run in parallel.

       This program is a part of the Middleman System (mdm).

OPTIONS

       The mdm.screen command has two optional options.

       -c iospec
              The iospec file (see below).

       -n slaves
              The number of mdm-slave process to start (default 6).

THE IOSPEC FILE

       mdm-master  uses  the  iospec  file to decide whether two commands interfere with each other, and it only
       runs two commands at the same time if they do not interfere.

       Each line of the iospec file specifies the I/O behavior of a program, unless the line starts with  a  '#'
       character, in which case the line is treated as comments and ignored.  The format is as follows:

              program spec spec ...

       program  names the program whose behavior you are specifying.  For each spec element, the first character
       indicates usage, and the remaining characters indicate resource.

       A resource that starts with a '-' character represents the argument of the corresponding program  option.
       A  resource that is an empty string represents a program argument.  A resource that is not empty and does
       not start with a '-' character represents the resource string itself.

       A usage is typically an upper-case character.  If two commands access the same  resource  with  different
       usage,  mdm-master  will not run these two commands at the same time.  Furthermore, if a command access a
       resource with ´W´ usage, mdm-master will not run it with any command that access the same resource in any
       way  (including 'W').  There is a special case: if usage is '0' and resource starts with a '-' character,
       it means that the resource program option does not take any arguments.

       All programs has an implicit spec 'Rglobal', so if you mark a program as 'Wglobal', it will not run while
       any other command is running.

       Here is an example to help clarify matters.  Suppose we have the following iospec file:

              cc W-o 0-c R
              rm W

       Then these two commands can run at the same time:

              cc -o pa pa.o lib.o
              cc -o pb pb.o lib.o

       These two commands cannot run at the same time:

              cc -o pa.o -c pa.c
              cc -o pa pa.o lib.o

       And these two commands also cannot run at the same time:

              cc -o pa pa.o lib.o
              rm pa

EXIT STATUS

       The exit status of mdm.screen is 0.

EXAMPLE

       Here is what you do to decompress all files with .gz extension in the current directory tree.

              mdm.screen find . -iname '*.gz' -exec mdm-run gunzip {} \;

       Since  we run find under mdm.screen and invoking gunzip under mdm-run, we specify that we wish to run the
       gunzip commands in parallel.

SEE ALSO

       mdm-run(1), mdm-sync(1), ncpus(1)