Y must be a simple empty vector but is ignored.

The result R is an integer vector of signal counts. The length of the vector is system dependent. On AIX 32-bit it is 63 on AIX 64-bit it is 256 but code should not rely on the length.

Each element is a count of the number of signals that have been generated since the last call to this function, or since the start of the process. R[1] is the number of occurrences of signal 1 (SIGHUP), R[2] the number of occurrences of signal 2, and so forth.

Each time the function is called it zeros the counts; it is therefore inadvisable to call it in more than one APL thread.

Currently, only SIGHUP, SIGINT, SIGQUIT, SIGTERM and SIGWINCH are counted and all other corresponding elements of R are 0.