-
For
>>, the answer is similar to the > redirection, except that the
file is opened with the flags [O_WRONLY; O_APPEND; O_CREAT].
- For
2>, the answer is similar to the > redirection, except that
dup2 fd stderr is executed instead of dup2 fd stdout
- For
2>1, we must call dup2 stderr stdout before executing
the command.
- For
<<, the shell sh must create a temporary file in
/tmp containing the lines that follow << and execute the
command with its standard input redirected from this file. Another
solution is to connect the command’s standard input to the output of a
pipe and let a child process write the lines following << on the
input of that pipe.
* * *