The description below is from the book DOS the Easy Way by Everett Murdock Ph.D.
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Type: External (3.3 and later)
Syntax:
FC [d:][path]filename [d:][path]filename [/A][/C][/L][/Lb n]
[/N][/T][/W]
[/(number)]
or (for binary comparisons)
FC [d:][path]filename [d:][path]filename [/B][/number]
Purpose: Displays the differences between two files or sets of
files.
Discussion
FC reports differences between the two files you specify. FC first
displays the
name of the first file to compare. Next, it displays the lines that
differ
between the two files. Next, it displays the first line that matches in
the two
files. FC next displays the name of the second file, followed by the
lines that
are different followed by the first line that matches.
The FC command requires enough system memory (RAM) to compare 100 lines.
If
system memory is limited, FC will make comparisons between the number of
lines
that can fit into available memory. Be aware that this can change the
results
of a comparison.
Options
/A - Instead of displaying all the lines that do not match (in an
ASCII
comparison), the program displays only the lines that begin and end each
set of
differences.
/B - Used for a binary comparison of files. The files are compared
byte-by-byte. Mismatches are displayed as a relative address from the
beginning
of the file. Unless you specify the /L switch, the program will
automatically
assume you want to use this type of comparison when the compared files
have a
.COM, .EXE, .SYS, .BIN, .OBJ, or .LIB filename extension.
/C - Ignores the case of letters in the compared files. All letters
are
considered as upper case.
/L - Used for an ASCII comparison of files. Unless you specify the /B
switch, the program will automatically assume you want to use this type
of
comparison for all files that do not have a .COM, .EXE, .SYS, .BIN, .OBJ,
or
.LIB filename extension.
/Lb n - Sets the line buffer to n number of lines. The amount of
memory
used for holding lines being compared is normally enough to store about
100
lines. Use this option to reset the buffer (memory space) to n lines.
If more
than this number of consecutive lines is found to differ, the program
will
terminate the comparison and display an error message.
/N - Used to turn on the display of line numbers while carrying out
an ASCII
comparison.
/T - Turn off the display of tabs as spaces in an eight column
display
format.
/W - Compresses tabs and spaces during the comparison.
/(number) - The number of lines that must match after the program finds
a
difference between the compared files (if fewer lines match, the matching
lines
are displayed as differences). If you do not use this option, the number
of
lines to match between the files is two.
Example
To compare the text file LETTER.TXT with the file MEMO2.TXT on drive B
(an ASCII
comparison), enter
fc /l letter.txt b:memo2.txt
To carry out a binary comparison of the files CHECK.EXE and CHECK2.EXE,
enter
fc /b check.exe check2.exe
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