acct(5) - Linux manual page (original) (raw)
acct(5) File Formats Manual acct(5)
NAME top
acct - process accounting fileSYNOPSIS 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)](../man2/acct.2.html) 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 _compt_ 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 _acutime_, _acstime_, and _acetime_ fields measure time in "clock
ticks"; divide these values by _sysconf(SCCLKTCK)_ to convert
them to seconds.Version 3 accounting file format Since Linux 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 cuid and acgid 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
Although it is present on most systems, it is not standardized,
and the details vary somewhat between systems.STANDARDS top
None.HISTORY top
glibc 2.6.
Process accounting originated on BSD.NOTES top
Records in the accounting file are ordered by termination time of
the process.
Up to and including Linux 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)](../man5/proc.5.html), defines
settings that control the behavior of process accounting when disk
space runs low.SEE ALSO top
[lastcomm(1)](../man1/lastcomm.1.html), [acct(2)](../man2/acct.2.html), [accton(8)](../man8/accton.8.html), [sa(8)](../man8/sa.8.html)COLOPHON top
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man-pages@man7.orgLinux man-pages 6.10 2024-05-02 acct(5)
Pages that refer to this page:lastcomm(1), acct(2), user_namespaces(7), accton(8), sa(8)