sysconf,pathconf, and fpathconf

sysconf,pathconf, and fpathconf

Answer

Rule	sysconf	pathconf	fpathconf
Definition	Use to get configuration information at run time	gets a value for configuration option name for the filename path.	gets a value for the configuration option name for the open file descriptor fd.
Prototype	#include<unistd.h>   long sysconf(int name);	#include<unistd.h> long pathconf(char *path, int name);	#include<unistd.h> long fpathconf(int fd, int name);

The following test_config.C illustrates the use of sysconf, pathcong and fpathconf:

#define _POSIX_SOURCE #define _POSIX_C_SOURCE 199309L #include<stdio.h> #include<iostream.h> #include<unistd.h> int main() { int res; if((res=sysconf(_SC_OPEN_MAX))==-1) perror(“sysconf”); else cout<<”OPEN_MAX:”<<res<<endl; if((res=pathconf(“/”,_PC_PATH_MAX))==-1) perror(“pathconf”); else cout<<”max path name:”<<(res+1)<<endl; if((res=fpathconf(0,_PC_CHOWN_RESTRICTED))==-1) perror(“fpathconf”); else cout<<”chown_restricted for stdin:”<<res<<endl; return 0; }