Setting preferences for comparing files
5 stars based on
This manual is for GNU Diffutils version 3. Computer users often find occasion to ask how two files differ. Perhaps one file is a newer version of the other file. Or maybe the two files started out as identical copies but were changed by different people. You can use the diff command to show differences between two files, or each corresponding file in two directories.
This set of differences is often called a diff or patch. For files that are identical, diff normally produces no output; for binary non-text files, diff normally reports only that they are different.
You can use the cmp command to show the byte and line numbers where java compare two files binary trading files differ. A way to compare two files character by character is the Emacs command M-x compare-windows. You can use the diff3 command to show differences among three files. You can use the set of differences produced by diff to distribute updates to text files such as program source code to other people.
This method is especially useful when the differences are small compared to the complete files. Given diff output, you can use the patch program to update, or patcha copy of the file. If you think of diff as subtracting one file from another to produce their difference, you can think of patch as adding the difference to one file to reproduce the other. This manual first concentrates on making diffs, and later shows how to use diffs to update files. Wayne Davison designed and implemented the unified output format.
The basic algorithm is described by Eugene W. Myers, Software—Practice and Experience Vol. Related algorithms are surveyed by Alfred V. Aho in section 6. GNU diff3 was written by Randy Smith.
GNU sdiff was written by Thomas Lord. Parts of this manual are adapted from a manual page written by Larry Wall, with his permission. Output FormatsPrevious: There are several ways to think about the differences between two files. One way to think of the differences is as a series of lines that were deleted from, inserted in, or changed in one file to produce java compare two files binary trading other file. It can report the java compare two files binary trading lines in several formats, which have different purposes.
GNU diff can show whether files are different without detailing the differences. It also provides ways to suppress certain kinds of differences that are not important to you. Most commonly, such differences are changes in the amount of white space between words or lines. These options can accumulate; for example, you can ignore changes in both white space and alphabetic case. Another way to think of the differences between two files is as a sequence of pairs of bytes that can be either identical or different.
As a result, it is often more useful than diff for comparing binary files. For text files, cmp is useful mainly when you want to know only whether two files are identical, or whether one file is a prefix of the other.
To illustrate the effect that considering changes byte by byte can have compared with considering them line by line, think of what happens if a single newline character is added to the beginning of a file. If that file is then compared with an otherwise identical file that lacks the newline at the beginning, diff will report that a blank line has been added to the file, while cmp will report that almost every byte of the two files differs.
Its output is designed to make it easy to inspect two different sets of changes to the same file. These commands compare input files without necessarily reading them. For example, if diff is asked simply to report whether two files differ, and it discovers that the files have different sizes, it need not read them to do its job. White SpaceUp: When comparing two files, diff finds sequences of lines common to both files, interspersed with groups of differing lines called hunks.
Comparing two identical files yields one sequence of common lines and no hunks, because no lines differ. Comparing two entirely different files yields no common lines and one large hunk that contains all lines of both files.
In general, there are many ways to match up lines between two given files. But its output is usually close to the shortest possible. You can adjust this tradeoff with the --minimal -d option see diff Performance. Blank LinesPrevious: The --ignore-tab-expansion -E option ignores the distinction between tabs and spaces on input. A tab is considered to be equivalent to the number of spaces to the next tab stop see Tabs.
The --ignore-trailing-space -Z option ignores white space at line end. The --ignore-space-change -b option is stronger than -E and -Z combined. It ignores white space at line end, and considers all other sequences of one or more white space characters within a line to be equivalent.
The --ignore-all-space -w option is stronger still. It ignores differences even if one line has white space where the other line has none.
White space characters java compare two files binary trading tab, vertical tab, form feed, carriage return, and space; some locales may define additional characters to be white space. For many other programs newline is also a white space character, but diff is a line-oriented program and a newline character always ends a line. Hence the -w or --ignore-all-space option does not ignore newline-related changes; it ignores only other white space changes.
Specified LinesPrevious: The --ignore-blank-lines -B option ignores changes that consist entirely of blank lines. With this option, for example, a file containing. Normally this option affects only lines that are completely empty, but if you also specify an option that ignores trailing spaces, lines are also affected if they look empty but contain white space. Case FoldingPrevious: Blank LinesUp: You should escape regular expressions that contain shell metacharacters to prevent the shell from expanding them.
However, -I only ignores the insertion or deletion of lines that contain the regular expression if every changed line in the hunk—every insertion and every deletion—matches the regular expression.
In other words, for each nonignorable change, diff prints the complete set of changes in its vicinity, including the ignorable ones. You can specify more than one regular expression for java compare two files binary trading to ignore by using more than one -I option.
Specified LinesUp: To request this, use the -i or --ignore-case option. Case FoldingUp: In this format, instead of showing the differences between the files, diff simply reports whether files differ.
The --brief -q option selects this output format. This format is especially useful when comparing the contents of two directories. It is also much faster than doing the normal line by line comparisons, because diff can stop analyzing the files as soon as it knows that there are any differences. You can also get a brief indication of whether two files differ by java compare two files binary trading cmp. For files that are identical, cmp produces no output. When the files differ, by default, cmp outputs the byte and line number where the first difference occurs, or reports that one file is a prefix of the other.
You can use the -s--quietor --silent option to suppress that information, so that cmp java compare two files binary trading no output and reports whether the files differ using only its exit java compare two files binary trading see Invoking cmp.
Unlike diffcmp cannot compare directories; it can only compare two files. If diff thinks that either of the two files it is comparing is binary a non-text fileit normally treats that pair of files much as if the summary output format had been selected see Briefand reports only that the binary files are different. This is because line by line comparisons are usually not meaningful for binary files.
This does not count as trouble, even though the resulting output does not capture all the differences. If every byte in that part of the file is java compare two files binary trading, diff considers the file to be text; otherwise it considers the file to be binary. Sometimes you might want to force diff to consider files to be text. For example, you might be comparing text files that contain null characters; diff would erroneously decide that those are non-text files.
Or you might be comparing documents that are in a format used by a word processing system that uses null characters to indicate special formatting.
You can force diff to consider all files to be text files, and compare them line by line, by using the --text -a option. If the files you compare using this option do not in fact contain text, they will probably contain few newline characters, and the diff output will consist of hunks showing differences between long lines of whatever characters the files contain.
You can also force diff to report only whether files differ but not how. Use the --brief -q option for this. In operating systems that distinguish between text and binary files, java compare two files binary trading normally reads and writes all data as text.
Use the --binary option to force diff to read and write binary data instead. However, many personal computer operating systems represent the end of a line with a carriage return followed by a newline. On such systems, diff normally ignores these carriage returns on input and generates them at the end of each output line, but with the --binary option diff treats each carriage return as just another input character, and does not generate a carriage return at the end of each output line.
This can be useful when dealing with non-text files that are meant to be interchanged with POSIX-compliant systems. The --strip-trailing-cr causes diff to treat java compare two files binary trading lines that end in carriage return followed by newline as if they end in plain newline. This can be useful when comparing text that is imperfectly imported from many personal computer operating systems.
This option affects how lines are read, which in turn affects how they are compared and output. If you want to compare two files byte by byte, you can use the cmp program with the --verbose -l option to show the values of each differing byte in the two java compare two files binary trading.