Named pipes using MKS Toolkit

UNIX for Advanced & Expert Users
1

I'm not sure whether or not this question really belongs in this forum and will accept rebuke should I have mistakenly put it in the wrong place (hopefully the rebuke will be accompanied by an answer, though)

I wish to implement named pipe communication between two process using MKS Toolkit. I have used the "mkfifo" command to create the named pipe in the appropriate directory, but I cannot find a way, from the command line, to write to the pipe without destroying it. If I do something like "ls > mypipe.fifo" then the pipe is destroyed and the mypipe.fifo is converted to a normal text file.

I found a reference to using the MKS call to popen() in order to open a pipe, but am not able (allowed) to write and install a user-written c program on the MKS installation. Thus I am looking for some method of writing to the named pipe using a command line call and haven't found anything in the documentation or by searching the web.

2

Try this:

#!/bin/bash
# reader.sh
pipe=/tmp/mypipe
trap "rm -f $pipe" EXIT

if [[ ! -p $pipe ]]; then
    mkfifo $pipe
fi

while true
do
    if read line <$pipe; then
        if [[ "$line" == 'quit' ]]; then
            break
        fi
        echo $line
    fi
done


#!/bin/bash
# writer.sh
pipe=/tmp/mypipe

if [[ ! -p $pipe ]]; then
    echo "Reader not running"
    exit 1
fi


if [[ "$1" ]]; then
    echo "$1" >$pipe
else
    echo "Hello from $$" >$pipe
fi

usage:

sh ./reader.sh &
./writer.sh "hello"
./writer.sh
./writer.sh "quit"

Is that what you meant? This works in "standard" bash - I don't have mks so I don't know if bash under mks is complete implementation.

3

Hello Jim,

thanks for the quick response, but unfortunately every redirection to write to the pipe, be it through "echo" or "cat", changes the file type from a pipe to a normal sequential in the MKS toolkit. I've tried with DOS, sh and bash and the behaviour is the same in all cases.