The Linux Programming Interface

596 Chapter 28

In the output, we see one line for each process that was created in the shell session.

The ulimit and echo commands are shell built-in commands, so they don’t result in

the creation of new processes. Note that the entry for sleep appeared in the account-

ing file after the cat entry because the sleep command terminated after the cat

command.

Most of the output is self-explanatory. The flags column shows single letters

indicating which of the ac_flag bits is set in each record (see Table 28-1). Section 26.1.3

describes how to interpret the termination status values shown in the term. status

column.

Listing 28-2: Displaying data from a process accounting file

–––––––––––––––––––––––––––––––––––––––––––––––––––––– procexec/acct_view.c

#include <fcntl.h>

#include <time.h>

#include <sys/stat.h>

#include <sys/acct.h>

#include <limits.h>

#include "ugid_functions.h" /* Declaration of userNameFromId() */

#include "tlpi_hdr.h"

#define TIME_BUF_SIZE 100

static long long /* Convert comp_t value into long long */

comptToLL(comp_t ct)

{

const int EXP_SIZE = 3; /* 3-bit, base-8 exponent */

const int MANTISSA_SIZE = 13; /* Followed by 13-bit mantissa */

const int MANTISSA_MASK = (1 << MANTISSA_SIZE) - 1;

long long mantissa, exp;

mantissa = ct & MANTISSA_MASK;

exp = (ct >> MANTISSA_SIZE) & ((1 << EXP_SIZE) - 1);

return mantissa << (exp * 3); /* Power of 8 = left shift 3 bits */

}

int

main(int argc, char *argv[])

{

int acctFile;

struct acct ac;

ssize_t numRead;

char *s;

char timeBuf[TIME_BUF_SIZE];

struct tm *loc;

time_t t;

if (argc != 2 || strcmp(argv[1], "--help") == 0)

usageErr("%s file\n", argv[0]);

acctFile = open(argv[1], O_RDONLY);

if (acctFile == -1)

errExit("open");