ACCT(5)                                             Linux Programmer's Manual                                            ACCT(5)



NAME
       acct - process accounting file

SYNOPSIS
       #include <sys/acct.h>

DESCRIPTION
       If  the kernel is built with the process accounting option enabled (CONFIG_BSD_PROCESS_ACCT), then calling acct(2) starts
       process accounting, for example:

           acct("/var/log/pacct");

       When process accounting is enabled, the kernel writes a record to the accounting file as each process on the system  ter-
       minates.  This record contains information about the terminated process, and is defined in <sys/acct.h> as follows:

           #define ACCT_COMM 16

           typedef u_int16_t comp_t;

           struct acct {
               char ac_flag;           /* Accounting flags */
               u_int16_t ac_uid;       /* Accounting user ID */
               u_int16_t ac_gid;       /* Accounting group ID */
               u_int16_t ac_tty;       /* Controlling terminal */
               u_int32_t ac_btime;     /* Process creation time
                                          (seconds since the Epoch) */
               comp_t    ac_utime;     /* User CPU time */
               comp_t    ac_stime;     /* System CPU time */
               comp_t    ac_etime;     /* Elapsed time */
               comp_t    ac_mem;       /* Average memory usage (kB) */
               comp_t    ac_io;        /* Characters transferred (unused) */
               comp_t    ac_rw;        /* Blocks read or written (unused) */
               comp_t    ac_minflt;    /* Minor page faults */
               comp_t    ac_majflt;    /* Major page faults */
               comp_t    ac_swaps;     /* Number of swaps (unused) */
               u_int32_t ac_exitcode;  /* Process termination status
                                          (see wait(2)) */
               char      ac_comm[ACCT_COMM+1];
                                       /* Command name (basename of last
                                          executed command; null-terminated) */
               char      ac_pad[X];    /* padding bytes */
           };

           enum {          /* Bits that may be set in ac_flag field */
               AFORK = 0x01,           /* Has executed fork, but no exec */
               ASU   = 0x02,           /* Used superuser privileges */
               ACORE = 0x08,           /* Dumped core */
               AXSIG = 0x10            /* Killed by a signal */
           };

       The  comp_t  data type is a floating-point value consisting of a 3-bit, base-8 exponent, and a 13-bit mantissa.  A value,
       c, of this type can be converted to a (long) integer as follows:

           v = (c & 0x1fff) << (((c >> 13) & 0x7) * 3);

       The ac_utime, ac_stime, and ac_etime fields measure time in "clock ticks"; divide these values by sysconf(_SC_CLK_TCK) to
       convert them to seconds.

   Version 3 Accounting File Format
       Since   kernel   2.6.8,   an  optional  alternative  version  of  the  accounting  file  can  be  produced  if  the  CON-
       FIG_BSD_PROCESS_ACCT_V3 option is set when building the kernel.  With this option is set,  the  records  written  to  the
       accounting  file  contain  additional  fields, and the width of c_uid and ac_gid fields is widened from 16 to 32 bits (in
       line with the increased size of UID and GIDs in Linux 2.4 and later).  The records are defined as follows:

           struct acct_v3 {
               char      ac_flag;      /* Flags */
               char      ac_version;   /* Always set to ACCT_VERSION (3) */
               u_int16_t ac_tty;       /* Controlling terminal */
               u_int32_t ac_exitcode;  /* Process termination status */
               u_int32_t ac_uid;       /* Real user ID */
               u_int32_t ac_gid;       /* Real group ID */
               u_int32_t ac_pid;       /* Process ID */
               u_int32_t ac_ppid;      /* Parent process ID */
               u_int32_t ac_btime;     /* Process creation time */
               float     ac_etime;     /* Elapsed time */
               comp_t    ac_utime;     /* User CPU time */
               comp_t    ac_stime;     /* System time */
               comp_t    ac_mem;       /* Average memory usage (kB) */
               comp_t    ac_io;        /* Characters transferred (unused) */
               comp_t    ac_rw;        /* Blocks read or written
                                          (unused) */
               comp_t    ac_minflt;    /* Minor page faults */
               comp_t    ac_majflt;    /* Major page faults */
               comp_t    ac_swaps;     /* Number of swaps (unused) */
               char      ac_comm[ACCT_COMM]; /* Command name */
           };


VERSIONS
       The acct_v3 structure is defined in glibc since version 2.6.

CONFORMING TO
       Process accounting originated on BSD.  Although it is present on most systems, it is not standardized,  and  the  details
       vary somewhat between systems.

NOTES
       Records in the accounting file are ordered by termination time of the process.

       In  kernels  up  to  and  including 2.6.9, a separate accounting record is written for each thread created using the NPTL
       threading library; since Linux 2.6.10, a single accounting record is written for the entire process on termination of the
       last thread in the process.

       The  proc/sys/kernel/acct  file,  described  in proc(5), defines settings that control the behavior of process accounting
       when disk space runs low.

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

COLOPHON
       This page is part of release 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                                                      2008-06-15                                                    ACCT(5)