ACCT(5)

NAME
acct - execution accounting file

SYNOPSIS
#include <sys/acct.h>

DESCRIPTION
The kernel maintains the following acct information structure for all processes. If a process terminates, and accounting is enabled, the kernel calls the acct_process(9) 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 uint16_t comp_t;
    struct acct {
    	char	  ac_comm[16];	/* 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 */
    	uint16_t  ac_mem;	/* memory usage average */
    	comp_t	  ac_io;	/* count of IO blocks */
    	dev_t	  ac_tty;	/* controlling tty */
    #define	AFORK	0x01		/* fork'd but not exec'd */
    #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 */
    	uint8_t	  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
    void   acct_init(void);
    int    acct_process(struct lwp *);
    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, ACORE, and AXSIG.

The ASU flag is not recorded anymore because with the switch to kauth(9), the superuser model is optional and passing the affected process to every authorization call in order to record ASU in p_acflag, would require many source changes and would not reflect reality because the authorization decision might not have been done based on the secmodel_suser(9) model.

The ACOMPAT flag was never recorded in NetBSD; we could consider setting when the a process is running under emulation, but this is not currently done.

Both the ASU and the ACOMPAT flags are retained for source compatibility.

SEE ALSO
lastcomm(1), acct(2), execve(2), accton(8), sa(8), acct_process(9)

HISTORY
A acct file format appeared in AT&T UNIX.