Extension Exercises (The GNU Awk User’s Guide)
From Get docs
- Add functions to implement system calls such as
umask()to the file operations extension presented in C Code for chdir() and stat().
- Write an input parser that prints a prompt if the input is a from a “terminal” device. You can use the
isatty()function to tell if the input file is a terminal. (Hint: this function is usually expensive to call; try to call it just once.) The content of the prompt should come from a variable settable by
awk-level code. You can write the prompt to standard error. However, for best results, open a new file descriptor (or file pointer) on
/dev/ttyand print the prompt there, in case standard error has been redirected. Why is standard error a better choice than standard output for writing the prompt? Which reading mechanism should you replace, the one to get a record, or the one to read raw bytes?
- Write a wrapper script that provides an interface similar to ‘
sed -i’ for the “inplace” extension presented in Enabling In-Place File Editing.