Chap 10. I/O Redirection and Pipes

Chap 10. I/O Redirection and Pipes

* CLI Communication by I/O and PIPES 

* cmd $ Comm A B -> print difference

1) A & !B

2) B & !A

3) A & B

* The ">" operator can be used to treats files as variables of arbitrary size and structure

( cmd > writeFile , cmd < ReadFile )

* Fd - stdin 0 stdout 1 stderr 2 (FIXNUM) 

* If we open file -> then we receive "THE LOWEST FD" 

* Shell $ CMD > FD  

then, if you write stdout in code.c, but then we write FD.

in SHELL process stdout -> FD 

* How to Attach stdin to FILE

1) Close and Then 

2) open..close..dup..close Method3

3) open..dup2..close

* Execute (by fork) -> in child process fd

* Pipe - one Way channel to communicate with File

pipe(int fdArr[2])