Dear all,
If I login to a Unix system (general user account), will the unix system generate a history file?
If positve, will it stored the IP adress also?
Thanks and Regards
Penny Li
;) (2 Replies)
Hello all,
I'm ufs file system, how can u use the same disk in another machine with the data in tact? to make it clear, I've an ufs FS in a mount point /file1 ( 8GB). now they decide to reintall the OS. After the reinstall, how can i get the same data as it is? will mounting the disk as /file1... (3 Replies)
Hello all !
Could someone throw some light on whether there's a limit to the number of characters contained in the command string that is passed to the system() call in C.
Is it OS dependent? If yes, what are the limits for each?
Thanks. (4 Replies)
Hello,
I have few questions about file system in Unix and Linux.
1. What's the difference between Unix and Linux in their file system? Are they the same?
2. Is in Unix directory for administrator "/root" - like in Linux - Ubuntu or not?
3.Where is the users directory in Unix? Is it... (2 Replies)
in man system it talks about SIGCHLD will be blocked, and SIGINT and SIGQUIT will be ignored.
Does this signal stuff also happen in popen command?
(even though man popen says nothing about signals)
also if I am not using wait(&status) and I am using waitpid(pid, NULL, 0)
how would... (1 Reply)
Hi
I have created a perl script & running it using Linux machine. I want my script to die when system command is unsuccessful but script is dying even when system command gets executed successfully. :wall:
I am using the command below :-
system($cmd) || die "FAILED $!";
print "Hello";
... (2 Replies)
I'm currently studying for my exam, and is practicing with sample exam questions.
However there is a question asking "Name THREE UNIX Directory system calls" and the answer given is "opendir, closedir and readdir", however the next question ask "Why is a write directory system call not included... (1 Reply)
Hi,
The file system unix use a multilevel indexes access to disk, 12 direct blocks, 1 single indirect block, 1 double indirect block, 1 triple indirect block:
Assuming a:
block = 512 bytes,
pointer = 4 byte,
and there is a file of 200 blocks,
how many disk access is needed to read the block... (1 Reply)
Hi,
I am on Solaris 10 server which is running Veritas. It's E420 server with two drives. I don't know much about Veritas. The other guy who works on this, on vacation this week. :-) Any way, looks like I have hard drive issue on the server.
When I do iostat -E. I see this.
sd0... (4 Replies)
Discussion started by: samnyc
4 Replies
LEARN ABOUT SUSE
system
SYSTEM(3) Linux Programmer's Manual SYSTEM(3)NAME
system - execute a shell command
SYNOPSIS
#include <stdlib.h>
int system(const char *command);
DESCRIPTION
system() executes a command specified in command by calling /bin/sh -c command, and returns after the command has been completed. During
execution of the command, SIGCHLD will be blocked, and SIGINT and SIGQUIT will be ignored.
RETURN VALUE
The value returned is -1 on error (e.g. fork(2) failed), and the return status of the command otherwise. This latter return status is in
the format specified in wait(2). Thus, the exit code of the command will be WEXITSTATUS(status). In case /bin/sh could not be executed,
the exit status will be that of a command that does exit(127).
If the value of command is NULL, system() returns nonzero if the shell is available, and zero if not.
system() does not affect the wait status of any other children.
CONFORMING TO
C89, C99, POSIX.1-2001.
NOTES
If the _XOPEN_SOURCE feature test macro is defined, then the macros described in wait(2) (WEXITSTATUS(), etc.) are made available when
including <stdlib.h>.
As mentioned, system() ignores SIGINT and SIGQUIT. This may make programs that call it from a loop uninterruptible, unless they take care
themselves to check the exit status of the child. E.g.
while (something) {
int ret = system("foo");
if (WIFSIGNALED(ret) &&
(WTERMSIG(ret) == SIGINT || WTERMSIG(ret) == SIGQUIT))
break;
}
Do not use system() from a program with set-user-ID or set-group-ID privileges, because strange values for some environment variables might
be used to subvert system integrity. Use the exec(3) family of functions instead, but not execlp(3) or execvp(3). system() will not, in
fact, work properly from programs with set-user-ID or set-group-ID privileges on systems on which /bin/sh is bash version 2, since bash 2
drops privileges on startup. (Debian uses a modified bash which does not do this when invoked as sh.)
In versions of glibc before 2.1.3, the check for the availability of /bin/sh was not actually performed if command was NULL; instead it was
always assumed to be available, and system() always returned 1 in this case. Since glibc 2.1.3, this check is performed because, even
though POSIX.1-2001 requires a conforming implementation to provide a shell, that shell may not be available or executable if the calling
program has previously called chroot(2) (which is not specified by POSIX.1-2001).
It is possible for the shell command to return 127, so that code is not a sure indication that the execve(2) call failed.
SEE ALSO sh(1), signal(2), wait(2), exec(3)COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2004-12-20 SYSTEM(3)