c - How to move file from one folder to different folder in linux

Question

How to move a particular file from one folder to another folder?

What I have tried,

#include <stdio.h>

int main() {
    FILE *tFile;
    if (tFile != NULL)
        tFile = NULL;
    if ((tFile = fopen("TempFile.txt", "rw")) == NULL) {
        return -1;
    }

    mv("TempFile.txt", "../MST");

    printf("Done Succesfully
");
    return 0;
}

Error :

test.c:17:2: warning: no newline at end of file
/tmp/ccKLWYNa.o(.text+0x5e): In function `main':
: undefined reference to `mv'
collect2: ld returned 1 exit status

Please guide me how can I do this.

Answer 1

You really should read Advanced Linux Programming and syscalls(2)

To move (from C) a file from one place to another in the same file system just use the rename(2) syscall.

At the very least, for your particular example, you'll need to code:

char* srcpath = "TempFile.txt"; // assume it is a variable path
char destpath[1024];
snprintf (destpath, sizeof(destpath), "../MST/%s", srcpath);
if (rename (srcpath, destpath)) {
   // something went wrong
   if (errno == EXDEV) {
      // copy data and meta data 
   } else { perror("rename"); exit(EXIT_FAILURE); };
} 
else { // the rename succeeded
}

^{If you really want to mv TempFile.txt ../MST/TempFile.txt specifically for TempFile.txt only you could just call rename("TempFile.txt", "../MST/TempFile.txt") and handle the error cases like I suggest. If you are sure that ../MST/lie in the same file system than . then EXDEV should not happen and you don't need to handle it particularly (but you do need to handle errors).}

If you want to move a file between two different file systems, you have to copy the data (and perhaps some of the meta-data) yourself (and then remove e.g. with unlink(2)) the original source file). You could detect that situation by various means: you could just try the rename and if errno (see errno(3)) is EXDEV you need to copy the file. Or you could use stat(2) to query the source file(and the destination directory) meta-data -e.g. its size and its file system.

Of course, you need to understand what are files on Linux (or Posix), in particular what is an inode.... See inode(7) and credentials(7)

You could have used system with /bin/mv (but be careful about strange characters -like spaces or semicolons- in the file paths, you need to escape them to avoid code injection), apparently you don't want to.

You should play with strace(1) (or perhaps also ltrace) on mv in various situations to understand what it is doing. Also, study the source code of GNU coreutils which provides /bin/mv notably in mv.c ...

Some extra C or C++ libraries may provide you with functions to move files (in the same filesystem they should do a rename, in different file systems they copy the source file data and perhaps some meta-data and unlink the source, so cannot be atomic), e.g. in C g_file_move (from Gio with Glib from Gnome), or in C++ copy_file -followed by remove in Boost, etc etc....

PS. For temporary files see tmpfile(3), mkstemp(3), etc...