linux中如何打开文件

cat filename.txt

less filename.txt

more filename.txt

vi filename.txt

vim filename.txt

nano filename.txt

with open('filename.txt', 'r') as file:
    content = file.read()
    print(content)

#include <stdio.h>

int main() {
    FILE *file = fopen("filename.txt", "r");
    if (file == NULL) {
        printf("Could not open file
");
        return 1;
    }

    char ch;
    while ((ch = fgetc(file)) != EOF) {
        putchar(ch);
    }

    fclose(file);
    return 0;
}

#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>

int main() {
    int fd = open("filename.txt", O_RDONLY);
    if (fd == -1) {
        perror("open");
        return 1;
    }

    char buffer[1024];
    ssize_t bytes_read;
    while ((bytes_read = read(fd, buffer, sizeof(buffer))) > 0) {
        write(STDOUT_FILENO, buffer, bytes_read);
    }

    close(fd);
    return 0;
}