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Compare two files and displays the differences between them.
Syntax: FC [/A] [/C] [/L] [/LBn] [/N] [/T] [/W] [/nnn] [/B] file1 file2
/A Abbreviate the ASCII output. Instead of displaying all lines,
FC will display the first and last lines that are different.
/C Ignore the case of letters.
/L Compare in ASCII mode. Display all lines that differ. This is
the default mode for files that are not EXE, COM, SYS, OBJ, LIB,
or BIN.
/LBn Sets the number of lines for the internal buffer. Default=100.
If the files have more than this many differences, FC will quit.
/N Display line numbers.
/T Do not expand tabs to spaces. Default is to expand tabs to
8-space stops during comparison.
/W Compress white space during comparison.
/nnn Specifies the number of lines that must match after a miscompare
for the files to be resychronized. Default=2.
/B Compare in binary mode. Does not attempt to resychronize after
a miscompare.
Reporting differences between files
When you use fc for an ASCII comparison, FreeDOS reports differences
between two files by displaying the first filename, followed by the
lines from filename1 that differ between files, followed by the first
line to match in both files. It then displays the second filename,
followed by the lines from filename2 that differ, followed by the first
line to match.
Using the /b switch
FreeDOS uses the following format to report mismatches found during a
binary comparison: xxxxxxxx: yy zz
The value of xxxxxxxx specifies the relative hexadecimal address for
the pair of bytes, measured from the beginning of the file. Addresses
start at 00000000; hexadecimal values for yy and zz represent mismatched
bytes from filename1 and filename2, respectively.
How fc uses memory
When comparing ASCII files, fc uses an internal buffer (large enough
to hold 100 lines) as storage. If the files are larger than the
buffer, fc compares what it can hold in the buffer. If fc does not
find a match in the loaded portions of the files, it stops and
displays the following error message:
Resynch failed. Files are too different.
When comparing binary files that are larger than available memory, fc
compares both files completely, overlaying the portions in memory
with the next portions from the disk. The output is the same as for
files that fit completely in memory.
Examples:
To make an ASCII comparison of two files named MONTLY.RPT and SALES.RPT
and display the results in abbreviated form, type:
fc /a monthly.rpt sales.rpt
To make a binary comparison of two files named PROFITS.BAT and NET.BAT,
type the following command:
fc /b profits.bat net.bat