Сравнение каталогов

$ diff каталог1 каталог2

Сравнение двоичных файлов

$ diff /bin/ls /usr/bin/lsvfs 

$ diff /bin/ls /usr/bin/lscpu

Binary files /bin/ls and /usr/bin/ls... differ

Сравнение текстовых файлов

$ cat hello.c
#include <stdio.h>
main () {
        printf("Hello World\n");
}

$ cp hello.c hello.c.old

$ cat hello.c
#include <stdio.h>
main () {
        printf("Hello World Again\n");
}

$ diff hello.c.old hello.c 
3c3
<       printf("Hello World\n");
---
>       printf("Hello World Again\n");

$ diff hello.c.old hello.c > hello.patch

$ mv hello.c.old hello.c

$ patch hello.c hello.patch

$ cat hello.c
#include <stdio.h>
main () {
        printf("Hello World Again\n");
}