---
name: "acct"
section: "5"
platform: "macos"
package: "xnu"
version: "12377.121.6"
release: "macOS 26.5"
platforms: ["linux", "freebsd", "openbsd", "macos"]
url: "https://new.carta.tech/acct/5"
---

# acct(5)

execution accounting file

## 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 kernel calls the [acct(2)](/acct/2.md) 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)](/execve/2.md), 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, ASU, ACOMPAT, ACORE and ASIG.

## SEE ALSO

[lastcomm(1)](/lastcomm/1.md), [acct(2)](/acct/2.md), [execve(2)](/execve/2.md), [accton(8)](/accton/8.md), [sa(8)](/sa/8.md)

## HISTORY

A **acct** file format appeared in Version 7 AT&T UNIX.