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📚 NAME

fork, wait, waitpid – 🧵 basic process management

🚀 Quick Reference

Use Case	Command	Description
👶 Create a child process	fork()	Returns 0 in child, PID in parent, or -1 on error
⏳ Wait for a specific child	waitpid(pid)	Waits for process with given PID to finish
⏳ Wait for any child	wait()	Waits for the first child process to terminate

📖 SYNOPSIS

@load "fork"

pid = fork()

ret = waitpid(pid)

ret = wait();

📝 DESCRIPTION

The fork extension adds three functions, as follows.

🔧 fork()

This function creates a new process. The return value is zero in the child and the process-id number of the child in the parent, or -1 upon error. In the latter case, ERRNO indicates the problem. In the child, PROCINFO["pid"] and PROCINFO["ppid"] are updated to reflect the correct values.

🔧 waitpid()

This function takes a numeric argument, which is the process-id to wait for. The return value is that of the waitpid(2) system call.

🔧 wait()

This function waits for the first child to die. The return value is that of the wait(2) system call.

🐛 BUGS

• ❌ There is no corresponding exec() function.
• 🔧 The interfaces could be enhanced to provide more facilities, including pulling out the various bits of the return status.

💡 EXAMPLE

@load "fork"
...
if ((pid = fork()) == 0)
    print "hello from the child"
else
    print "hello from the parent"

📚 SEE ALSO

• GAWK: Effective AWK Programming, filefuncs(3am), fnmatch(3am), inplace(3am), ordchr(3am), readdir(3am), readfile(3am), revoutput(3am), rwarray(3am), time(3am).
• 📄 fork(2), wait(2), waitpid(2).

✍️ AUTHOR

Arnold Robbins, arnold@skeeve.com.

📄 COPYING PERMISSIONS

Copyright © 2012, 2013, 2018, Free Software Foundation, Inc.

• ✅ Permission is granted to make and distribute verbatim copies of this manual page provided the copyright notice and this permission notice are preserved on all copies.
• ✅ Permission is granted to copy and distribute modified versions of this manual page under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.
• ✅ Permission is granted to copy and distribute translations of this manual page into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Foundation.

Free Software Foundation · Feb 02 2018 · FORK(3am)

📚 NAME 🚀 Quick Reference 📖 SYNOPSIS 📝 DESCRIPTION 🐛 BUGS 💡 EXAMPLE 📚 SEE ALSO ✍️ AUTHOR 📄 COPYING PERMISSIONS