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time(1) [netbsd man page]

TIME(1) 						    BSD General Commands Manual 						   TIME(1)

time -- time command execution SYNOPSIS
time [-clp] command [argument ...] DESCRIPTION
The time utility executes and times command. After the command finishes, time writes the total elapsed time (wall clock time), (``real''), the CPU time spent executing command at user level (``user''), and the CPU time spent executing in the operating system kernel (``sys''), to the standard error stream. Times are reported in seconds. Available options: -c Displays information in the format used by the time builtin of csh(1). -l Lists resource utilization information. The contents of the command process's rusage structure are printed; see below. -p The output is formatted as specified by IEEE Std 1003.2-1992 (``POSIX.2''). Some shells, such as csh(1) and ksh(1), have their own and syntactically different built-in version of time. The utility described here is available as /usr/bin/time to users of these shells. Resource Utilization If the -l option is given, the following resource usage information is displayed in addition to the timing information: maximum resident set size average shared memory size average unshared data size average unshared stack size page reclaims page faults swaps block input operations block output operations messages sent messages received signals received voluntary context switches involuntary context switches Resource usage is the total for the execution of command and any child processes it spawns, as per wait4(2). FILES
<sys/resource.h> EXIT STATUS
The time utility exits with one of the following values: 1-125 An error occurred in the time utility. 126 The command was found but could not be invoked. 127 The command could not be found. Otherwise, the exit status of time will be that of command. SEE ALSO
csh(1), ksh(1), clock_gettime(2), getrusage(2) STANDARDS
The time utility conforms to IEEE Std 1003.2-1992 (``POSIX.2''). BUGS
The granularity of seconds on microprocessors is crude and can result in times being reported for CPU usage which are too large by a second. BSD
November 9, 2011 BSD

Check Out this Related Man Page

GETRUSAGE(2)							System Calls Manual						      GETRUSAGE(2)

getrusage - get information about resource utilization SYNOPSIS
#include <sys/time.h> #include <sys/resource.h> #define RUSAGE_SELF 0 /* calling process */ #define RUSAGE_CHILDREN -1 /* terminated child processes */ getrusage(who, rusage) int who; struct rusage *rusage; DESCRIPTION
Getrusage returns information describing the resources utilized by the current process, or all its terminated child processes. The who parameter is one of RUSAGE_SELF or RUSAGE_CHILDREN. The buffer to which rusage points will be filled in with the following structure: struct rusage { struct timeval ru_utime; /* user time used */ struct timeval ru_stime; /* system time used */ long ru_maxrss; long ru_ixrss; /* integral shared text memory size */ long ru_idrss; /* integral unshared data size */ long ru_isrss; /* integral unshared stack size */ long ru_minflt; /* page reclaims */ long ru_majflt; /* page faults */ long ru_ovly; /* overlay changes */ long ru_nswap; /* swaps */ long ru_inblock; /* block input operations */ long ru_oublock; /* block output operations */ long ru_msgsnd; /* messages sent */ long ru_msgrcv; /* messages received */ long ru_nsignals; /* signals received */ long ru_nvcsw; /* voluntary context switches */ long ru_nivcsw; /* involuntary context switches */ }; The fields are interpreted as follows: ru_utime the total amount of time spent executing in user mode. ru_stime the total amount of time spent in the system executing on behalf of the process(es). ru_maxrss the maximum resident set size utilized (in kilobytes). ru_ixrss an "integral" value indicating the amount of memory used by the text segment that was also shared among other processes. This value is expressed in units of kilobytes * seconds-of-execution and is calculated by summing the number of shared mem- ory pages in use each time the internal system clock ticks and then averaging over 1 second intervals. ru_idrss an integral value of the amount of unshared memory residing in the data segment of a process (expressed in units of kilo- bytes * seconds-of-execution). ru_isrss an integral value of the amount of unshared memory residing in the stack segment of a process (expressed in units of kilo- bytes * seconds-of-execution). ru_minflt the number of page faults serviced without any I/O activity; here I/O activity is avoided by "reclaiming" a page frame from the list of pages awaiting reallocation. ru_majflt the number of page faults serviced that required I/O activity. the number of times a process requested a text overlay switch - only available under 2_10BSD. ru_nswap the number of times a process was "swapped" out of main memory. ru_inblock the number of times the file system had to perform input. ru_outblock the number of times the file system had to perform output. ru_msgsnd the number of IPC messages sent. ru_msgrcv the number of IPC messages received. ru_nsignals the number of signals delivered. ru_nvcsw the number of times a context switch resulted due to a process voluntarily giving up the processor before its time slice was completed (usually to await availability of a resource). ru_nivcsw the number of times a context switch resulted due to a higher priority process becoming runnable or because the current process exceeded its time slice. NOTES
The numbers ru_inblock and ru_outblock account only for real I/O; data supplied by the caching mechanism is charged only to the first process to read or write the data. ERRORS
The possible errors for getrusage are: [EINVAL] The who parameter is not a valid value. [EFAULT] The address specified by the rusage parameter is not in a valid part of the process address space. SEE ALSO
gettimeofday(2), wait(2) BUGS
There is no way to obtain information about a child process that has not yet terminated. 4th Berkeley Distribution May 13, 1986 GETRUSAGE(2)
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