ACCT
acct - switch process accounting on or off
#include <unistd.h> int acct(const char *filename);
When called with the name of an existing file as argument, accounting is turned on, records for each terminating process are appended to filename as it terminates. An argument of NULL causes accounting to be turned off.
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
SVr4 (but not POSIX). SVr4 documents EACCES, EBUSY, EFAULT, ELOOP, ENAMETOOLONG, ENOTDIR, ENOENT, EPERM and EROFS error conditions, but no ENOSYS.
No accounting is produced for programs running when a crash occurs. In particular, nonterminating processes are never accounted for.
3 pages link to acct(2):