errno man page on DigitalUNIX

Man page or keyword search:  
man Server   12896 pages
apropos Keyword Search (all sections)
Output format
DigitalUNIX logo
[printable version]

errno(5)							      errno(5)

       errno - Returns error condition value

       #include <errno.h>

       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 refer‐
       ence 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

       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  pro‐
       gram  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

       main() {
	   char filespec[SLENGTH], *eol;
	   int opret;
	   while (TRUE) {
	       printf("Enter file to be checked: ");
	       fgets(filespec, SLENGTH, stdin);
	       if ((eol = strchr(filespec, '\n')) != NULL) {
		   *eol = '\0';	 /* Replace newline with null */
		   if (*filespec == '\0') return; /* exit program */
		   opret = open(filespec,O_RDONLY,0);
		   if (opret > 0)
		     printf("%s: File exists\n",filespec);
		   else if (errno == ENOENT)
		     printf("%s: File does not exist\n",filespec);
		   else if (errno == ENOTDIR)
		     printf("%s: Prefix in path is not a directory\n",

	       } else		/* Line entered too long */
		 printf("Line entered is too long\n");
	   } }

       To  ensure  that	 your programs are portable, you should not explicitly
       declare errno to be an extern int in your program.  You should rely  on
       the type int declaration in the <errno.h> include file.	Full use.

       Functions: intro(2), perror(3), strerror(3)


List of man pages available for DigitalUNIX

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
Vote for polarhome
Free Shell Accounts :: the biggest list on the net