(libc.info.gz) Initial Signal Actions

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(libc.info.gz) Flags for Sigaction

(libc.info.gz) Signal Actions

 
 24.3.6 Initial Signal Actions
 -----------------------------
 
 When a new process is created ( Creating a Process), it inherits
 handling of signals from its parent process.  However, when you load a
 new process image using the `exec' function ( Executing a File),
 any signals that you've defined your own handlers for revert to their
 `SIG_DFL' handling.  (If you think about it a little, this makes sense;
 the handler functions from the old program are specific to that
 program, and aren't even present in the address space of the new
 program image.)  Of course, the new program can establish its own
 handlers.
 
    When a program is run by a shell, the shell normally sets the initial
 actions for the child process to `SIG_DFL' or `SIG_IGN', as
 appropriate.  It's a good idea to check to make sure that the shell has
 not set up an initial action of `SIG_IGN' before you establish your own
 signal handlers.
 
    Here is an example of how to establish a handler for `SIGHUP', but
 not if `SIGHUP' is currently ignored:
 
      ...
      struct sigaction temp;
 
      sigaction (SIGHUP, NULL, &temp);
 
      if (temp.sa_handler != SIG_IGN)
        {
          temp.sa_handler = handle_sighup;
          sigemptyset (&temp.sa_mask);
          sigaction (SIGHUP, &temp, NULL);
        }
 

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(libc.info.gz) Flags for Sigaction

(libc.info.gz) Signal Actions