C - Linux System Call like touch

tolosenc · 12-10-2012 12:19AM #1

I'm sure many of you are familiar with the "touch" command on Linux. Essentially "touch program.c" creates a blank file called program.c in the current directory.

I've been playing around with system calls lately, and was wondering if there was one that did this? I've been operating off the following code in lieu:

int touch(char* fn)
{
    FILE *fp;
    fp = fopen(fn, "w");

    if(fp == NULL)
    {
        return -1;
    }

    fclose(fp);

    return 0;
}

Not sure if this should go here or the Linux forum, so I'll post it there too.

irishd · 12-10-2012 02:50AM

creat() ?

Adds: or better, mknod() ?

moycullen14 · 12-10-2012 10:17AM

tolosenc wrote: »
I'm sure many of you are familiar with the "touch" command on Linux. Essentially "touch program.c" creates a blank file called program.c in the current directory.

I've been playing around with system calls lately, and was wondering if there was one that did this? I've been operating off the following code in lieu:
int touch(char* fn)
{
    FILE *fp;
    fp = fopen(fn, "w");

    if(fp == NULL)
    {
        return -1;
    }

    fclose(fp);

    return 0;
}
Not sure if this should go here or the Linux forum, so I'll post it there too.

This isn't doing what touch does at all.

The intention of touch is to alter access & modification times on files - one effect is that a file is created IF AND ONLY IF it doesn't exist.

your code changes the contents of a file - in the case above it wipes all the data.

touch is based around creat & stat/fstat system calls

Have a look at:
http://src.gnu-darwin.org/src/usr.bin/touch/touch.c.html

C - Linux System Call like touch

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