The number following "real" is the time that elapsed from when the command started running until it finished (this is sometimes referred to as wall clock time); the number following "user" is the time that was attributed to your user code while the command was running; and the number following "sys" is the time that was attributed to OS (kernel) code while the command was running. On a multi-processor system, user time + sys time could be larger than real time if multiple cores were running different parts of your code at the same time. Real time could easily be much more than the sum of user time + sys time if your code was waiting for I/O or was delayed while other code was being run on your system by other processes.
PS Note that when the shell you're using prints time output in the format:
the 1st number (ending with 'u') is user time, the 2nd number (ending with 's') is sys time, and the 3rd part is wall clock time. The percentage at the end is how much of the system the command was using during the life of the command: ((user + sys) / real) * 100.
Last edited by Don Cragun; 07-18-2013 at 09:58 PM..
Reason: Add PS comparing different time output formats.
I wondered if someone could point out the differences between the time commmand and usr/bin/time and the accuracy one might have over another.
Also, is there a website or two a person could maybe link for me to describe the differences?
Thank you for your time. (2 Replies)
Our Aix Unix has one issue.
If I type xedit &
after 30 minutes, xedit auto shut down.
If I type xedit
xedit will run forward.
I feel this & doesn't perform as it should be.
When I use &, system consider this process as idle.
How to fix this issue?
Does this mean unix env... (12 Replies)
I have noticed a few posts asking questions about c shell scripting these past few days. This a good read for those that currently or are thinking about writing a csh script:
Csh Programming Considered Harmful (9 Replies)
How can I run a here document on just one line? I ask, because I need to issue it from C++ as a system() or similar command and for security reasons I don't want to write out a shell script file from the program and run it.
For example, how could I write:
passwd test <<EOF
n3wp3ss... (3 Replies)
Hi friends,
I hope everyone is doing well and fine. I have always been hearing that C/C++ are relatively low-level as compared to Java/C# etc. Could you please tell me some low-level qualities of C/C++? And I think disk deframenters are written in C/C++, please correct me if I am wrong. And please... (5 Replies)
Ive a problem that I'm reaching out for help.
Ive written (With bits and pieces) of script that is not running as expected or is having an issue causing processes to spiral out of control.
The script does this:
Unloads a UV database server
Tars up a few folders
Transfers the file to... (11 Replies)
I am trying to issue the time command on a program so I can see execution times but it is returning all zeroes. Like this:
time pdriver arg1 arg2
0.000u 0.000s 0:00.00 0.0% 0+0k 0+0io 0pf+0w
"0+0k 0+0io 0pf+0w" --> The "0+0io" may change sometimes to a different number.
How can I run the... (2 Replies)
Greetings all,
On a RedHat System - I am issuing a command from script.sh that will add a file extension to a listing of files in a directory. It works, but I need to script from having an extension added as well.
Here is what I have tried to no luck:
for file in `ls * | awk ' /\./{print... (6 Replies)
Hi,
Using ksh, I have set up aliases (which work fine) in my user's .profile like this:
alias ll = 'ls -lrt'
alias cls = 'clear'
How do I call these same aliases so that they will work after issuing this: ? su - user
I do not want to add aliases to the su shell's .profile or .kshrc. (7 Replies)
Discussion started by: ocbit
7 Replies
LEARN ABOUT NETBSD
time
TIME(1) BSD General Commands Manual TIME(1)NAME
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