ACCT(5) BSD File Formats Manual 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, and accounting is enabled, the ker-
nel 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_short comp_t;
struct acct {
char ac_comm[10]; /* name of command */
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 */
short ac_mem; /* memory usage average */
comp_t ac_io; /* count of IO blocks */
dev_t ac_tty; /* controlling tty */
#define AFORK 0x01 /* forked but not execed */
#define ASU 0x02 /* used super-user permissions */
#define ACOMPAT 0x04 /* used compatibility mode */
#define ACORE 0x08 /* dumped core */
#define AXSIG 0x10 /* killed by a signal */
char 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
struct vnode *acctp;
#endif
If a terminated 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 of more of the following flags in ac_flag: AFORK, ACORE and ASIG.
The ASU and ACOMPAT flags are no longer recorded by the system, but are retained for source compatibility.
SEE ALSO lastcomm(1), acct(2), execve(2), accton(8), sa(8)HISTORY
A acct file format appeared in Version 7 AT&T UNIX.
BSD December 22, 2006 BSD
Check Out this Related Man Page
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 account-
ing, 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
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 3.44 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)