linux commands to compare two files

[root@vikas current_task]# whatis cmp
cmp (1) - compare two files
cmp (1p) - compare two files
[root@vikas current_task]# whatis comp
comp: nothing appropriate
[root@vikas current_task]# whatis comm
comm (1) - compare two sorted files line by line
comm (1p) - select or reject lines common to two files
[root@vikas current_task]# whatis diff
diff (1) - find differences between two files
diff (1p) - compare two files
diff-jars (1) - output the differences between two JAR files