无法打印 C 中的 ls 错误之类的确切程序

Question

I created my own shell and trying to redirect the STDERR to output file.

I did:

dup2(output_fd, 2);

and when I am executing child, I am using

error_message = strerror(errno);
 write(STDERR_FILENO, error_message, strlen(error_message));

but the problem is I am getting this error message only:

No such file or directory

whereas I should be getting

ls: cannot access '/no/such/file': No such file or directory

running program: ls /no/such/file > output

Answer 1

ls is printing the message ls: cannot access 'stuff': by itself - in ls.c file_failure(... "cannot access") call and file_failure() definition and error() is a standard function from error.h . There's even no strerror call in ls sources - error() in glibc sources calls it.

So write the message yourself, use fprintf(stderr to format your message, or you may use GNU extension erorr() if you want.

strerror should return just "No such file or directory" and this is the standard message from strerror for ENOENT . There is errno -l to list errors with strings in terminal and here is list of errors in glibc sources .