Compare the contents of two files or sets of files. Display any lines which do NOT match.

Syntax FC /B pathname1 pathname2 FC [options] pathname1 pathname2 Key /B : Perform a binary comparison. options /C : Do a case insensitive string comparison /A : Displays only first and last lines for each set of differences. /U : Compare files as UNICODE text files. /L : Compares files as ASCII text. (default) /N : Display line numbers (ASCII only) /LBn: Limit the number of lines that will be read, "n" sets a maximum number of mismatches after which the File Comparison will abort (resync failed) When FC aborts (resync failed) then "n" number of mismatches will be shown. /nnnn : Specify a number of consecutive lines that must match after a mismatch. This can be used to prevent the display of the two files from getting too out of sync /T : Do not expand tabs to spaces. /W : Compress white space (tabs and spaces) for comparison.

To compare sets of files, use wildcards in pathname1 and pathname2 parameters.

Powershell also has an Alias FC for the Format-Custom command, therefore to run the 'old' FC under powershell you need to explicitly run C:\windows\system32\fc.exe

To identify 2 identical files use this syntax:

FC file1.txt file2.txt | FIND "FC: no dif" > nul IF ERRORLEVEL 1 goto :s_files_are_different


If two files are compared and the four lines of text match as follows

1: different

2: same

3: same

4: different

Specifying /nnnn =2 the file compare will display the 4th line and continue

Specifying /nnnn =3 the file compare will halt at the 4th line (files too different)

Specifying /LB1 the file compare will halt after the first line

# Oh lord won't you buy me a Mercedes Benz, my friends all drive Porsches, I must make amends # - Janice Joplin


COMP - Compare two files and display any characters which do NOT match

FIND - Search for a text string in a file

FINDSTR - Search for strings in files

WinDiff - GUI to compare files

Powershell: Compare-Object - Compare the properties of objects, e.g. compare content of files.

Equivalent bash command (Linux): cmp - Compare two files