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(libc.info)Signal Messages

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Signal Messages
---------------

   We mentioned above that the shell prints a message describing the
signal that terminated a child process.  The clean way to print a
message describing a signal is to use the functions `strsignal' and
`psignal'.  These functions use a signal number to specify which kind
of signal to describe.  The signal number may come from the termination
status of a child process (Note: Process Completion) or it may come
from a signal handler in the same process.

 - Function: char * strsignal (int SIGNUM)
     This function returns a pointer to a statically-allocated string
     containing a message describing the signal SIGNUM.  You should not
     modify the contents of this string; and, since it can be rewritten
     on subsequent calls, you should save a copy of it if you need to
     reference it later.

     This function is a GNU extension, declared in the header file
     `string.h'.

 - Function: void psignal (int SIGNUM, const char *MESSAGE)
     This function prints a message describing the signal SIGNUM to the
     standard error output stream `stderr'; see Note: Standard
     Streams.

     If you call `psignal' with a MESSAGE that is either a null pointer
     or an empty string, `psignal' just prints the message
     corresponding to SIGNUM, adding a trailing newline.

     If you supply a non-null MESSAGE argument, then `psignal' prefixes
     its output with this string.  It adds a colon and a space
     character to separate the MESSAGE from the string corresponding to
     SIGNUM.

     This function is a BSD feature, declared in the header file
     `signal.h'.

   There is also an array `sys_siglist' which contains the messages for
the various signal codes.  This array exists on BSD systems, unlike
`strsignal'.