ACCT(5) File Formats Manual ACCT(5)

acctexecution accounting file

#include <sys/acct.h>

The kernel maintains the following acct information structure for all processes. If a process terminates, and accounting is enabled, the kernel calls the acct(2) function call to prepare and append the record to the accounting file.

/*
 * Accounting structures; these use a comp_t type which is a 3 bits base 8
 * exponent, 13 bit fraction ``floating point'' number.  Units are 1/AHZ
 * seconds.
 */
typedef u_short comp_t;

struct acct {
	char	ac_comm[10];	/* name of command */
	comp_t	ac_utime;	/* user time */
	comp_t	ac_stime;	/* system time */
	comp_t	ac_etime;	/* elapsed time */
	time_t	ac_btime;	/* starting time */
	uid_t	ac_uid;		/* user id */
	gid_t	ac_gid;		/* group id */
	short	ac_mem;		/* memory usage average */
	comp_t	ac_io;		/* count of IO blocks */
	dev_t	ac_tty;		/* controlling tty */
#define	AFORK	0x01		/* forked but not execed */
#define	ASU	0x02		/* used super-user permissions */
#define	ACOMPAT	0x04		/* used compatibility mode */
#define	ACORE	0x08		/* dumped core */
#define	AXSIG	0x10		/* killed by a signal */
	char	ac_flag;	/* accounting flags */
};

/*
 * 1/AHZ is the granularity of the data encoded in the comp_t fields.
 * This is not necessarily equal to hz.
 */
#define	AHZ	64

#ifdef KERNEL
struct vnode	*acctp;
#endif

If a terminated process was created by an execve(2), the name of the executed file (at most ten characters of it) is saved in the field ac_comm and its status is saved by setting one of more of the following flags in ac_flag: AFORK, ASU, ACOMPAT, ACORE and ASIG.

lastcomm(1), acct(2), execve(2), accton(8), sa(8)

A acct file format appeared in Version 7 AT&T UNIX.

June 5, 1993 macOS 14.4