NAME | SYNOPSIS | DESCRIPTION | VERSIONS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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

NAME         top

       acct - process accounting file

SYNOPSIS         top

       #include <sys/acct.h>

DESCRIPTION         top

       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 terminates.  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 CONFIG_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         top

       The acct_v3 structure is defined in glibc since version 2.6.

CONFORMING TO         top

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

NOTES         top

       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         top

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

COLOPHON         top

       This page is part of release 4.07 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                            2008-06-15                          ACCT(5)