I/O Redirection

How does a shell implement output redirection (e.g., ls > output.txt) between fork() and exec()?

The shell modifies the kernel's file system table to redirect all writes from fd 1 to the file

The shell passes the filename as a special argument to exec(), which handles the redirection internally

The shell opens output.txt and uses dup2() to replace stdout (fd 1) with the file's descriptor, so when exec() runs ls, its stdout writes to the file

The shell captures ls's output in a buffer after exec() returns, then writes it to the file