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UNIX for Advanced & Expert Users
URGENT Help required regarding the use of FORK system call
Post 8123 by rwb1959 on Friday 5th of October 2001 05:15:12 PM
10-05-2001
The previous guru's are quite correct.
I might even suggest that you forget about fork(), wait(),
SIGCHLD, etc. and just launch 5 different instances of the
same program with say a file name as an argument...
#!/bin/ksh
myprog file1 > /tmp/file1.$$ &
kid1pid=$!
myprog file2 > /tmp/file2.$$ &
kid2pid=$!
....
myprog file5 > /tmp/file3.$$ &
kid5pid=$!
# at this point you wait on the kids
wait
# here you can assemble the files...
Cwd=`pwd`
cd /tmp
for i in `ls file?.*`
do
cat $i >> $Cwd/newfile.$$
done
rm -f file?.*
cd $Cwd
exit 0
...so... it ain't pretty, it ain't slick or elegant, hell, it ain't even C
but it is simple and will work by Monday
I might even suggest that you forget about fork(), wait(),
SIGCHLD, etc. and just launch 5 different instances of the
same program with say a file name as an argument...
#!/bin/ksh
myprog file1 > /tmp/file1.$$ &
kid1pid=$!
myprog file2 > /tmp/file2.$$ &
kid2pid=$!
....
myprog file5 > /tmp/file3.$$ &
kid5pid=$!
# at this point you wait on the kids
wait
# here you can assemble the files...
Cwd=`pwd`
cd /tmp
for i in `ls file?.*`
do
cat $i >> $Cwd/newfile.$$
done
rm -f file?.*
cd $Cwd
exit 0
...so... it ain't pretty, it ain't slick or elegant, hell, it ain't even C
but it is simple and will work by Monday
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LEARN ABOUT PLAN9
env
ENV(3) Library Functions Manual ENV(3) NAME
env - environment variables SYNOPSIS
bind #e /env /env/var1 /env/var2 ... DESCRIPTION
The env device serves a one-level directory containing files with arbitrary names and contents. The intention is that the file name is the name of an environment variable (see rc(1)), and the content is the variable's current value. When a fork(2) system call creates a new process, both the parent and the child continue to see exactly the same files in the env device: changes made in either process can be noticed by the other. In contrast, an rfork system call with the RFENVG bit set (see fork(2)) causes a split: initially both process groups see the same environment files, but any changes made in one process group cannot be noticed by the other. An rfork with RFCENVG splits and then clears the environment. SEE ALSO
rc(1), fork(2) SOURCE
/sys/src/9/port/devenv.c BUGS
A write starting at an offset after the current extent of a file yields an error instead of zero filling. ENV(3)