Write History

Task

Implement the function write_history

• Opens a file in append mode, write the command to it, and close the file
• If fopen() fails, call perror("open") and return -1
• If successful, return 0
• Each command should be on its own line in the file

Input Format: Each line is filepath:command

Function Signature

// Append command to the history file at filepath.
// Return 0 on success, -1 on error.
int write_history(const char* filepath, const char* command);

Important File I/O Functions

• fopen(filepath, "a") → Open file in append mode (creates if doesn’t exist)
• fprintf(file, "%s\n", command) → Write formatted string to file
• fclose(file) → Close the file

---

Example

$ gcc write_history.c -o write_history
$ ./write_history
history.txt:ls -l
success
history.txt:pwd
success
history.txt:echo hello
success
$ cat history.txt
ls -l
pwd
echo hello
$ ./write_history
/invalid/path.txt:test
open: No such file or directory

---

Code

#include <stdio.h>
 
int write_history(const char* filepath, const char* command){
	FILE* file = fopen(filepath, "a");
	if(file == NULL){
		perror("open");
		return -1;
	}
	
	fprintf(file, "%s\n", command);
	fclose(file);
	return 0;
}