Using the system errno is very important in C programming. All system calls will tell you there is an error by returning a -1, or NULL, or EOF, but only the errno variable, which is set by the system can tell you what the error is. To use it in a program, you need simply include the errno header file and define it as an external int.
You can also get a textual description using the perror(3C) function.
A little function I use in most of my programs for displaying system error messages follows. It uses the string function strerror(3C) to display a text message for any given errno value.
In Tru64 Unix, the 'errno' variable is not thread safe.
Could anybody help me about how to make it thread safe or how to check 'errno' in a Multithreaded program ????
The Programming process is like this.
There are some definite number of threads having their own task.
There is one... (2 Replies)
Hi,
I have a SPARCstation 10 with SunOS 5.6
This erlier was in a network and now I have it at home to make a webserver.
At fist there was NIS and things left from erlier. So the "Console login:" newer appered only the white window with sun logo topleft and some text info.
I made... (14 Replies)
Hello,
I need to make a lib with pthread, when I run my make file all is good. But when I run my test program, I test errno in the begining and is already set to 251. Is it normal ??? What can I modify in my Makefile to have errno set to 0 ???
Thanks
$make
gcc -D_REENTRANT -shared -fpic... (3 Replies)
Hey, Can I assume that for certain function calls, errno can never be set to a certain value.
More specifically, can I assume that for if the stat function call fails, the errno can never be or "No space left on device."
I am assuming that a read function cannot fail because of no space... (5 Replies)
here the program gives a odd result:
#include <stdio.h>
int main(){
perror("first");
perror("next");
return 0;
}
result:
first: Success
next: Illegal seek
why? any resonable explanation? i found no information about this in man pages.
thanks in advance (2 Replies)
If a process already has the entire file locked for read and write using newstruct.l_type = F_WRLCK; what would happen if another process would try to open it in read only mode using open(filename, O_RDONLY); ?
I want to check if the file exists and I want it to work even if another process has... (4 Replies)
Hi All,
I am getting an error message when I execute command “zlogin -C sunsrv4z5” on my root server.
INIT: Cannot stat /etc/inittab, errno: 2
INIT: Cannot stat /etc/inittab, errno: 2
As per my analysis it seems that some files inside /etc folder are deleted.
This server was... (14 Replies)
Dear all,
CentOS 6
After executing "yum update -y" command I am facing this error. Please help me out.
thanks in advance. Full error & error code is given as follow:
... (7 Replies)
(Apologies for any typos.)
OSX 10.12.3 AND Windows 10.
This is for the serious Python experts on at least 3.5.x and above...
In script format sys.stdout.write() AND sys.stderr.write() seems to work correctly.
Have I found a serious bug in the interactive sys.stdout.write() AND... (2 Replies)
Hi, I need to look at a recent copy of /usr/include/errno.h from AIX 7.2 to check some symbols. In particular, I'm curious if it defines EOWNERDEAD and ENOTRECOVERABLE. Can someone who has access to 7.2 please check for me? Thanks! (1 Reply)
Discussion started by: topcat
1 Replies
LEARN ABOUT OSF1
errno
errno(5) File Formats Manual errno(5)NAME
errno - Returns error condition value
SYNOPSIS
#include <errno.h>
DESCRIPTION
The errno external variable contains the most recent error condition set by a function. The symbolic values for errno are listed in the
intro reference page and in the ERRORS section of the individual reference pages for each function.
The exec() functions set errno to a value of 0 (zero) after successful completion. Typically, other functions only set errno to a nonzero
value.
EXAMPLES
The following program uses the value of errno to determine why the requested file could not be opened. If errno has one of the two tested
values, the program prints an appropriate message; otherwise, the program uses the error() function to print out the appropriate message.
This program does not have to set errno to a value of 0 (zero) because errno is tested only if the open() function has failed.
#include <errno.h> #include <stdio.h> #include <string.h> #include <fcntl.h> #include <sys/stat.h> #include <sys/types.h> #define SLENGTH
80
main() {
char filespec[SLENGTH], *eol;
int opret;
while (TRUE) {
printf("Enter file to be checked: ");
fgets(filespec, SLENGTH, stdin);
if ((eol = strchr(filespec, '
')) != NULL) {
*eol = '