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 or misbehaves in specific ways, 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_int16_t comp_t;
    struct acct {
    	char	  ac_comm[10];	/* command name */
    	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 */
    	u_int16_t ac_mem;	/* average memory usage */
    	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	AMAP	0x04		/* system call or stack mapping violation */
    #define	ACORE	0x08		/* dumped core */
    #define	AXSIG	0x10		/* killed by a signal */
    #define	APLEDGE	0x20		/* killed due to pledge violation */
    #define	ATRAP	0x40		/* memory access violation */
    #define	AUNVEIL	0x80		/* unveil access violation */
    	u_int8_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
    int	acct_process(struct proc *p);
    int	acct_shutdown(void);
    #endif

If a terminated or misbehaving 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 or more of the following flags in ac_flag:

AFORK
    A new process was created via fork(2) that was not followed by a call to execve(2).

ASU The process used super-user permissions. This flag is never set and is provided for source compatibility only.

ACOMPAT
    On VAX, this indicated that the process executed in PDP/11 compatibility mode. This flag is never set and is provided for source compatibility only.

ACORE
    The process terminated abnormally due to a signal and dumped core(5).

AXSIG
    The process was killed by a signal(3).

APLEDGE
    The process was killed due to a pledge(2) violation.

ATRAP
    The process was killed due to a memory access violation detected by a processor trap.

AUNVEIL
    The process attempted a file access that was prevented by unveil(2) restrictions. Note that this does not cause the process to terminate.

SEE ALSO
lastcomm(1), acct(2), execve(2), pledge(2), unveil(2), signal(3), core(5), accton(8), sa(8)

HISTORY
An acct file format first appeared in AT&T UNIX.