06-16-2011
Unix directory system calls question
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 in the above list?"
I'm not sure about the answer to this question so can anyone help me out?
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
What does the system call "dup" do?
What is the difference between dup and dup2
I have a fair idea of what it does but I am confused when its coming down to the exact details...
Please help me!:confused: (2 Replies)
Discussion started by: clickonline1
2 Replies
2. UNIX for Dummies Questions & Answers
Which system calls are made for operations cp and mv (2 Replies)
Discussion started by: gaurava99
2 Replies
3. UNIX for Dummies Questions & Answers
open, creat, read, write, lseek and close
Are they all primitive?
:confused:
*Another Question: is there a different between a system call, and an i/o system call? (2 Replies)
Discussion started by: PlunderBunny
2 Replies
4. Solaris
where can i find the differences in System calls between solaris and aix?
also is it possible to find a comprehensive list of them? (1 Reply)
Discussion started by: TECHRAMESH
1 Replies
5. Programming
why user is not able to switch from user to kernel mode by writing the function whose code is identical to system call. (1 Reply)
Discussion started by: joshighanshyam
1 Replies
6. BSD
what is the functions and relationship between fork,exec,wait system calls
as i am a beginer just want the fundamentals. (1 Reply)
Discussion started by: sangramdas
1 Replies
7. Programming
#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<stdlib.h>
int main( int argc,char *argv )
{
char buf;
int sourcefile,destfile,n;
if(argc!=3)
{
write(STDOUT_FILENO,"prgm1 <sourcefile> <destination file>\n",50);
... (6 Replies)
Discussion started by: c_d
6 Replies
8. UNIX for Dummies Questions & Answers
Hi all,
I am new here .
I want to know about system call in detail.
As system calls are also function .How system identifies it.:) (2 Replies)
Discussion started by: vishwasrao
2 Replies
9. UNIX for Dummies Questions & Answers
Hello,
how would i be able to call ps in C programming?
thanks,
---------- Post updated at 01:39 AM ---------- Previous update was at 01:31 AM ----------
here's the complete system call, ps -o pid -p %d, getpit() (2 Replies)
Discussion started by: l flipboi l
2 Replies
10. UNIX for Dummies Questions & Answers
Hi i am very new to programming in UNIX and don't understand the difference between a system call and a normal function call. Also can I implement system calls from within a program? If so could someone please give me an example of a system call from within a program. Lastly, when creating a... (1 Reply)
Discussion started by: bjhum33
1 Replies
DIRECTORY(3) Library Functions Manual DIRECTORY(3)
NAME
opendir, readdir, telldir, seekdir, rewinddir, closedir - directory operations
SYNOPSIS
#include <sys/types.h>
#include <sys/dir.h>
DIR *opendir(filename)
char *filename;
struct direct *readdir(dirp)
DIR *dirp;
long telldir(dirp)
DIR *dirp;
seekdir(dirp, loc)
DIR *dirp;
long loc;
rewinddir(dirp)
DIR *dirp;
closedir(dirp)
DIR *dirp;
DESCRIPTION
Opendir opens the directory named by filename and associates a directory stream with it. Opendir returns a pointer to be used to identify
the directory stream in subsequent operations. The pointer NULL is returned if filename cannot be accessed, or if it cannot malloc(3)
enough memory to hold the whole thing.
Readdir returns a pointer to the next directory entry. It returns NULL upon reaching the end of the directory or detecting an invalid
seekdir operation.
Telldir returns the current location associated with the named directory stream.
Seekdir sets the position of the next readdir operation on the directory stream. The new position reverts to the one associated with the
directory stream when the telldir operation was performed. Values returned by telldir are good only for the lifetime of the DIR pointer
from which they are derived. If the directory is closed and then reopened, the telldir value may be invalidated due to undetected direc-
tory compaction. It is safe to use a previous telldir value immediately after a call to opendir and before any calls to readdir.
Rewinddir resets the position of the named directory stream to the beginning of the directory.
Closedir closes the named directory stream and frees the structure associated with the DIR pointer.
Sample code which searchs a directory for entry ``name'' is:
len = strlen(name);
dirp = opendir(".");
for (dp = readdir(dirp); dp != NULL; dp = readdir(dirp))
if (dp->d_namlen == len && !strcmp(dp->d_name, name)) {
closedir(dirp);
return FOUND;
}
closedir(dirp);
return NOT_FOUND;
SEE ALSO
open(2), close(2), read(2), lseek(2), dir(5)
4.2 Berkeley Distribution September 24, 1985 DIRECTORY(3)