create a string that forms the command as run in command line,
and you have to run this " command " with " popen "
which would execute and you have would have execution time in the pipe, which you need to parse it and display!
Just a pointer !
If you need more explanations, shoot !
Hi,
I need to time a certain function in my C/C++ code and I am experiencing some difficulties. I timed it using wallclock time so I know that it takes approximately 500-600 microseconds with
gettimeofday(&start, NULL);
// my function call
gettimeofday(&end, NULL);
answer = (end.tv_sec -... (2 Replies)
Hello
I have problem with function 'time' to test my program for file copying .
How to run the function in my source code ?
I try something like that:
system("time"); < -- but this don't working (2 Replies)
Hi All,
I am using solaris and nawk.
Is there any time function in nawk which is simliar to the shell `date` function ?
Can any experts show any examples? (4 Replies)
HI ,
I need to get the timedifference between two values... which funcation will help
eg: difference betweem 19:22 and 19:43 should give 21 mins (2 Replies)
hello everybody!
i want to post a question. So, I use the command 'time a.out' to time the duration of the program a.out. The return value of this function was:
real 0m4.116s
user 0m4.112s
sys 0m0.016s
What i want is! I try to find a way to get (NOT manually) the value of real time.... (2 Replies)
HI
I have a Red Hat Enterprise with Real Time kernel.
Are you aware if there are C functions for this kernel or some code/library for this OS for measuring time more lightweight than clock_gettime and gettimeofday? THe hardware I have is NUMA.
Reading forums I found gethrtime but it is... (1 Reply)
Hello, I have made a Linux Shell Script that downloads 6 files from the Internet and then deletes them. Now i want to use the function "/usr/bin/time" and "bc" to calculate how long the avergate run time for the shell script is. I therefore need to do it 100 times. My shell script code is below:
... (6 Replies)
I want to print the difference (in days) between ($7) and the oldest record date ($6) based on unique ID ($5) on a new field. In addition, I want to subtract oldest date from recent dates(in days) ($6) for each unique ID ($5).
Here is the data looks like
7 81 1 47 32070 2010-12-14 ... (11 Replies)
Hi guys and gals...
I am writing a piece of code that is dash compliant and came across this error.
I have put it in the OSX section as that is what I am using.
I have no idea what the 'dash' version is but was installed about 6 months ago.
MBP, OSX 10.12.6, default terminal running dash on... (4 Replies)
Discussion started by: wisecracker
4 Replies
LEARN ABOUT NETBSD
pclose
POPEN(3) BSD Library Functions Manual POPEN(3)NAME
popen, pclose -- process I/O
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <stdio.h>
FILE *
popen(const char *command, const char *type);
int
pclose(FILE *stream);
DESCRIPTION
The popen() function ``opens'' a process by creating an IPC connection, forking, and invoking the shell. Historically, popen was implemented
with a unidirectional pipe; hence many implementations of popen only allow the type argument to specify reading or writing, not both. Since
popen is now implemented using sockets, the type may request a bidirectional data flow. The type argument is a pointer to a null-terminated
string which must be 'r' for reading, 'w' for writing, or 'r+' for reading and writing. In addition if the character 'e' is present in the
type string, the file descriptor used internally is set to be closed on exec(3).
The command argument is a pointer to a null-terminated string containing a shell command line. This command is passed to /bin/sh using the
-c flag; interpretation, if any, is performed by the shell.
The return value from popen() is a normal standard I/O stream in all respects save that it must be closed with pclose() rather than fclose().
Writing to such a stream writes to the standard input of the command; the command's standard output is the same as that of the process that
called popen(), unless this is altered by the command itself. Conversely, reading from a ``popened'' stream reads the command's standard
output, and the command's standard input is the same as that of the process that called popen().
Note that output popen() streams are fully buffered by default.
The pclose() function waits for the associated process to terminate and returns the exit status of the command as returned by wait4().
RETURN VALUES
The popen() function returns NULL if the fork(2), pipe(2), or socketpair(2) calls fail, or if it cannot allocate memory.
The pclose() function returns -1 if stream is not associated with a ``popened'' command, if stream has already been ``pclosed'', or if
wait4(2) returns an error.
ERRORS
The popen() function does not reliably set errno.
SEE ALSO sh(1), fork(2), pipe(2), socketpair(2), wait4(2), fclose(3), fflush(3), fopen(3), shquote(3), stdio(3), system(3)STANDARDS
The popen() and pclose() functions conform to IEEE Std 1003.2-1992 (``POSIX.2'').
HISTORY
A popen() and a pclose() function appeared in Version 7 AT&T UNIX.
BUGS
Since the standard input of a command opened for reading shares its seek offset with the process that called popen(), if the original process
has done a buffered read, the command's input position may not be as expected. Similarly, the output from a command opened for writing may
become intermingled with that of the original process. The latter can be avoided by calling fflush(3) before popen().
Failure to execute the shell is indistinguishable from the shell's failure to execute command, or an immediate exit of the command. The only
hint is an exit status of 127.
The popen() argument always calls sh(1), never calls csh(1).
BSD June 24, 2011 BSD