Implement Copy, move and delete a file in Linux- rename, unlink

Hi Guys,

In this post, we will see how to use Linux API's to perform copy, move and delete file operations

There is no direct Linux System Call for copy operation, we need to manually open one file in read mode, and other in create mode, and then start writing one by one

For move operation, the Linux System call is rename

 #include <stdio.h>

 int rename(const char *oldpath, const char *newpath);

For delete operation, the Linux System call is unlink

#include <unistd.h>

int unlink(const char *pathname);

Sample Code to use all the API's

	#include <stdio.h>
	#include <stdbool.h>
	#include <fcntl.h>
	#include <sys/stat.h>
	#include <sys/types.h>
	#include <errno.h>
	#define UTILITY_NAME "cp_mv_del"
	#define BUF_SIZE 1024
	static bool copy_file(char *src_path, char *dest_path)
	{
	int src_fd;
	int dest_fd;
	char buf[BUF_SIZE];
	ssize_t num_bytes_read;
	struct stat st;
	bool retval = false;
	if (!src_path || !dest_path) {
	printf("%s: Invalid arguments passed\n", UTILITY_NAME);
	return false;
	}
	//open src file in read mode, dest file in create mode
	src_fd = open(src_path, O_RDONLY);
	if (src_fd < 0) {
	printf("%s: Failed to open %s for reading, errno:%d\n",
	UTILITY_NAME, src_path, errno);
	return false;
	}
	dest_fd = open(dest_path, O_CREAT | O_WRONLY | O_TRUNC);
	if (dest_fd < 0) {
	printf("%s: Failed to open %s for writing, errno:%d\n",
	UTILITY_NAME, dest_path, errno);
	goto exit;
	}
	while ((num_bytes_read = read(src_fd, buf, BUF_SIZE)) > 0) {
	if (write(dest_fd, buf, num_bytes_read) != num_bytes_read) {
	printf("%s: Failed to write the whole buffer\n", UTILITY_NAME);
	goto exit;
	}
	}
	//Copy permissions
	if (stat(src_path, &st) != 0) {
	printf("%s: Failed to get file:%s status\n", UTILITY_NAME, src_path);
	goto exit;
	}
	if (chmod(dest_path, st.st_mode) != 0) {
	printf("%s: Failed to change mode of file%s\n", UTILITY_NAME, dest_path);
	goto exit;
	}
	retval = true;
	exit:
	if (src_fd >= 0)
	close(src_fd);
	if (dest_fd >= 0)
	close(dest_fd);
	return retval;
	}
	static bool mv(char *oldfile, char *newfile)
	{
	if (!oldfile || !newfile) {
	printf("%s: Invalid arguments passed\n", UTILITY_NAME);
	return false;
	}
	//check whether old file exist or not
	if (access(oldfile, F_OK) == -1) {
	printf("%s: File doesn't exist\n", UTILITY_NAME);
	return false;
	}
	if (rename(oldfile, newfile) == -1) {
	perror("Failed to rename");
	return false;
	}
	return true;
	}
	static bool del(char *path)
	{
	if (!path) {
	printf("%s: Invalid arguments passed\n", UTILITY_NAME);
	return false;
	}
	// check whether the path exists
	if (access(path, F_OK) == -1) {
	printf("%s: File doesn't exist\n", UTILITY_NAME);
	return false;
	}
	if (unlink(path) == -1) {
	perror("Failed to delete");
	return false;
	}
	return true;
	}
	int main(int argc, char *argv[])
	{
	if (copy_file("/tmp/hello.txt", "/tmp/world.txt")) {
	printf("Copy Successful\n");
	} else {
	printf("Copy failed\n");
	}
	if (mv("/tmp/hello.txt", "/tmp/file.txt")) {
	printf("Move successful\n");
	} else {
	printf("Move Failed\n");
	}
	if (del("/tmp/world.txt")) {
	printf("Delete Successful\n");
	} else {
	printf("Delete failed\n");
	}
	return 0;
	}

view raw cp_mv_del.c hosted with ❤ by GitHub

Output: