NAME

acct - per-process accounting file format

SYNOPSIS

#include <sys/types.h>
#include <sys/acct.h>

DESCRIPTION

Files produced as a result of calling acct(2) have records in the form defined by <sys/acct.h>, whose contents are:

typedef  ushort comp_t;  /* "floating point" */
          /* 13-bit fraction, 3-bit exponent  */
struct  acct
{
        char   ac_flag;    /* Accounting flag */
        char   ac_stat;    /* Exit status */
        uid_t  ac_uid;     /* Accounting user ID */
        gid_t  ac_gid;     /* Accounting group ID */
        dev_t  ac_tty;     /* control typewriter */
        time_t ac_btime;   /* Beginning time */
        comp_t ac_utime;   /* acctng user time in clock ticks */
        comp_t ac_stime;   /* acctng system time in clock ticks */
        comp_t ac_etime;   /* acctng elapsed time in clock ticks */
        comp_t ac_mem;     /* memory usage in clicks */
        comp_t ac_io;      /* chars trnsfrd by read/write */
        comp_t ac_rw;      /* number of block reads/writes */
        char   ac_comm[8]; /* command name */
};

extern  struct acct        acctbuf;
extern  struct vnode       *acctp;  /* vnode of accounting file */

#define AFORK  01          /* has executed fork, but no exec */
#define ASU    02          /* used super-user privileges */
#define ACCTF  0300        /* record type: 00 = acct */
#define AEXPND 040         /*Expanded Record Type*/

In ac_flag, the AFORK flag is turned on by each fork and turned off by an exec. The ac_comm field is inherited from the parent process and is reset by any exec. Each time the system charges the process with a clock tick, it also adds to ac_mem the current process size, computed as follows:

(data size) + (text size) / (number of in-core processes using text)

The value of ac_mem/(ac_stime+ac_utime) can be viewed as an approximation to the mean process size, as modified by text sharing.

The structure tacct, which resides with the source files of the accounting commands, represents the total accounting format used by the various accounting commands:

/*
 *  total accounting (for acct period), also for day
 */

struct tacct {
       uid_t          ta_uid;      /* userid */
       char           ta_name[8];  /* login name */
       float          ta_cpu[2];   /* cum. cpu time, p/np (mins) */
       float          ta_kcore[2]; /* cum kcore-minutes, p/np */
       float          ta_con[2];   /* cum. connect time, p/np, mins */
       float          ta_du;       /* cum. disk usage */
       long           ta_pc;       /* count of processes */
       unsigned short ta_sc;       /* count of login sessions */
       unsigned short ta_dc;       /* count of disk samples */
       unsigned short ta_fee;      /* fee for special services */
};

SEE ALSO

acct(2), exec(2), fork(2).
acct(1M) in the System Administrator's Reference Manual.
acctcom(1) in the User's Reference Manual.

NOTES

The ac_mem value for a short-lived command gives little information about the actual size of the command, because ac_mem may be incremented while a different command (e.g., the shell) is being executed by the process.