data1 Specifies location and name(s) of first file(s) to compare. data2 Specifies location and name(s) of second files to compare. /D Displays differences in decimal format. /A Displays differences in ASCII characters. /L Displays line numbers for differences. /N=number Compares only the first specified number of lines in each file. /C Disregards case of ASCII letters when comparing files. /OFF[LINE] Do not skip files with offline attribute set.
To compare sets of files, use wildcards in data1 and data2 parameters."
"The title is misleading, since the author doesn't really want a full diff. He only wants to know IF 2 files are different. The distinction is important if the files are big.
Checksumming methods will obviously read both files entirely. As far as I could tell, Windows' FC and COMP both also read the entire files, even if there was a difference in the first bytes.
As John T suggests, get GNU diffutils, which includes cmp.exe. With big files, cmp will be a lot faster than COMP or FC.
That is if you need it to be a command-line tool. If you can use a GUI shareware, Total Commander has a ""Compare Files"" command, and a ""Synchronize dirs"" command which can be set to compare files by content. Both are extremely fast."
