typically you run this under bash. process working and starting concurently, but are running by the shell pararelly. how it is possible?

1. if it isn't last command in pipe, create unnamed pipe with pair of sockets
2. fork
3. in child reassign stdin/stdout to sockets if it's needed (for first process in pipe stdin is not reassigned, the same for last process and his stdout)
4. in child EXEC specified command with arguments that sweep out original shell code, but leaves all opened by them sockets. child process ID will not be changed because this is the same child process
5. concurently with child but pararelly under main shell go to step 1.

system not quarantee how fast exec will be executed and specified command starts. it's independed to the shell, but system. this is because:

ps auxww| grep ps | cat

once show grep and/or ps command, and next now. it depends how fast kernel really start processes using system exec function.

Typically you run this under bash. process working and starting concurrently, but are running by the shell in parallel. How is it possible?

1. if it isn't last command in pipe, create unnamed pipe with pair of sockets
2. fork
3. in child reassign stdin/stdout to sockets if it's needed (for first process in pipe stdin is not reassigned, the same for last process and his stdout)
4. in child EXEC specified command with arguments that sweep out original shell code, but leaves all opened by them sockets. child process ID will not be changed because this is the same child process
5. concurrently with child but parallel under main shell go to step 1.

system not guarantee how fast exec will be executed and specified command starts. it's independent to the shell, but system. This is because:

ps auxww| grep ps | cat

once show grep and/or ps command, and next now. It depends how fast kernel really start processes using system exec function.