Advanced Programming in the UNIX® Environment

ptg10805159

4

Files and Director ies

4.1 Introduction

In the previous chapter we covered the basic functions that perform I/O. The

discussion centered on I/O for regular files—opening a file, and reading or writing a

file. We’ll now look at additional features of the file system and the properties of a file.

We’ll start with thestatfunctions and go through each member of thestatstructure,

looking at all the attributes of a file. In this process, we’ll also describe each of the

functions that modify these attributes: change the owner,change the permissions, and

so on.We’ll also look in moredetail at the structure of a UNIX file system and symbolic

links. Wefinish this chapter with the functions that operate on directories, and we

develop a function that descends through a directory hierarchy.

4.2 stat,fstat,fstatat,and lstatFunctions

The discussion in this chapter centers on the fourstatfunctions and the information

they return.

#include <sys/stat.h>

int stat(const char *restrictpathname,struct stat *restrict buf);

int fstat(intfd,struct stat *buf);

int lstat(const char *restrictpathname,struct stat *restrictbuf);

int fstatat(intfd,const char *restrictpathname,

struct stat *restrict buf,intflag);

All four return: 0 if OK,−1 on error

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