# latexdiff - Online in the Cloud

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### PROGRAM:

#### NAME

latexdiff - determine and markup differences between two latex files

#### SYNOPSIS

latexdiff [ OPTIONS ] old.tex new.tex > diff.tex

#### DESCRIPTION

Briefly, latexdiff is a utility program to aid in the management of revisions of latex
documents. It compares two valid latex files, here called "old.tex" and "new.tex", finds
significant differences between them (i.e., ignoring the number of white spaces and
position of line breaks), and adds special commands to highlight the differences. Where
visual highlighting is not possible, e.g. for changes in the formatting, the differences
are nevertheless marked up in the source.

The program treats the preamble differently from the main document. Differences between
the preambles are found using line-based differencing (similarly to the Unix diff command,
but ignoring white spaces). A comment, ""%DIF >"" is appended to each added line, i.e. a
line present in "new.tex" but not in "old.tex". Discarded lines
are deactivated by prepending ""%DIF <"". Changed blocks are preceded by comment lines
giving information about line numbers in the original files. Where there are
insignificant differences, the resulting file "diff.tex" will be similar to "new.tex". At
the end of the preamble, the definitions for latexdiff markup commands are inserted. In
differencing the main body of the text, latexdiff attempts to satisfy the following
guidelines (in order of priority):

1. If both "old.tex" and "new.tex" are valid LaTeX, then the resulting "diff.tex" should
also be valid LateX. (NB If a few plain TeX commands are used within "old.tex" or
"new.tex" then "diff.tex" is not guaranteed to work but usually will).

2. Significant differences are determined on the level of individual words. All
significant differences, including differences between comments should be clearly
marked in the resulting source code "diff.tex".

3. If a changed passage contains text or text-producing commands, then running "diff.tex"
through LateX should produce output where added and discarded passages are highlighted.

4. Where there are insignificant differences, e.g. in the positioning of line breaks,
"diff.tex" should follow the formatting of "new.tex"

For differencing the same algorithm as diff is used but words instead of lines are
compared. An attempt is made to recognize blocks which are completely changed such that
they can be marked up as a unit. Comments are differenced line by line but the number of
spaces within comments is ignored. Commands including all their arguments are generally
compared as one unit, i.e., no mark-up is inserted into the arguments of commands.
However, for a selected number of commands (for example, "\caption" and all sectioning
commands) the last argument is known to be text. This text is split into words and
differenced just as ordinary text (use options to show and change the list of text
commands, see below). As the algorithm has no detailed knowledge of LaTeX, it assumes all
pairs of curly braces immediately following a command (i.e. a sequence of letters
beginning with a backslash) are arguments for that command. As a restriction to condition
1 above it is thus necessary to surround all arguments with curly braces, and to not
insert extraneous spaces. For example, write

\section{\textem{This is an emphasized section title}}

and not

\section {\textem{This is an emphasized section title}}

or

\section\textem{This is an emphasized section title}

even though all varieties are the same to LaTeX (but see --allow-spaces option which
allows the second variety).

For environments whose content does not conform to standard LaTeX or where graphical
markup does not make sense all markup commands can be removed by setting the PICTUREENV
configuration variable, set by default to "picture" and "DIFnomarkup" environments; see
--config option). The latter environment ("DIFnomarkup") can be used to protect parts of
the latex file where the markup results in illegal markup. You have to surround the
offending passage in both the old and new file by "\begin{DIFnomarkup}" and
"\end{DIFnomarkup}". You must define the environment in the preambles of both old and new
documents. I prefer to define it as a null-environment,

"\newenvironment{DIFnomarkup}{}{}"

but the choice is yours. Any markup within the environment will be removed, and generally
everything within the environment will just be taken from the new file.

It is also possible to difference files which do not have a preamble.
In this case, the file is processed in the main document mode, but the definitions of the
markup commands are not inserted.

All markup commands inserted by latexdiff begin with ""\DIF"". Added blocks containing
words, commands or comments which are in "new.tex" but not in "old.tex" are marked by
"\DIFdelend". Within added blocks all text is highlighted with "\DIFadd" like this:
"\DIFadd{Added text block}" Selected `safe' commands can be contained in these text blocks
as well (use options to show and change the list of safe commands, see below). All other
commands as well as braces "{" and "}" are never put within the scope of "\DIFadd". Added
comments are marked by prepending ""%DIF > "".

Within deleted blocks text is highlighted with "\DIFdel". Deleted comments are marked by
prepending ""%DIF < "". Non-safe command and curly braces within deleted blocks are
commented out with ""%DIFDELCMD < "".

#### OPTIONS

Preamble
The following options determine the visual markup style by adding the appropriate command
definitions to the preamble. See the end of this section for a description of available
styles.

--type=markupstyle or -t markupstyle
Add code to preamble for selected markup style. This option defines "\DIFadd" and
"\DIFdel" commands. Available styles:

CULINECHBAR CFONTCBHBAR BOLD"

[ Default: "UNDERLINE" ]

--subtype=markstyle or -s markstyle
Add code to preamble for selected style for bracketing commands (e.g. to mark changes
"\DIFdelend" commands. Available styles: "SAFE MARGIN COLOR DVIPSCOL ZLABEL
ONLYCHANGEDPAGE (LABEL)*"

[ Default: "SAFE" ] * Subtype "LABEL" is deprecated

--floattype=markstyle or -f markstyle
Add code to preamble for selected style which replace standard marking and markup
commands within floats (e.g., marginal remarks cause an error within floats so
marginal marking can be disabled thus). This option defines all "\DIF...FL" commands.

[ Default: "FLOATSAFE" ]

--encoding=enc or -e enc
Specify encoding of old.tex and new.tex. Typical encodings are "ascii", "utf8",
"latin1", "latin9". A list of available encodings can be obtained by executing

"perl -MEncode -e 'print join ("\n",Encode-"encodings( ":all" )) ;' >

[Default encoding is utf8 unless the first few lines of the preamble contain an
invocation "\usepackage[..]{inputenc}" in which case the encoding chosen by this
command is asssumed. Note that ASCII (standard latex) is a subset of utf8]

--preamble=file or -p file
Insert file at end of preamble instead of generating preamble. The preamble must
\DIFdelbegin,\DIFdelend,\DIFdel{..}," and varieties for use within floats
\DIFdelFL{..}" (If this option is set -t, -s, and -f options are ignored.)

--packages=pkg1,pkg2,..
Tell latexdiff that .tex file is processed with the packages in list loaded. This is
normally not necessary if the .tex file includes the preamble, as the preamble is
automatically scanned for "\usepackage" commands. Use of the --packages option
disables automatic scanning, so if for any reason package specific parsing needs to be
switched off, use --packages=none. The following packages trigger special behaviour:

"amsmath"
Configuration variable MATHARRREPL is set to "align*" (Default: "eqnarray*").
(Note that many of the amsmath array environments are already recognised by
default as such)

"endfloat"
Ensure that "\begin{figure}" and "\end{figure}" always appear by themselves on
a line.

"hyperref"
"\DIFdeltex" and define new "\DIFadd" and "\DIFdel" commands, which provide a
wrapper for these commands, using them for the text but not for the link
defining command (where any markup would cause errors).

"apacite"
Redefine the commands recognised as citation commands.

"siunitx"
Treat "\SI" as equivalent to citation commands (i.e. protect with "\mbox" if
markup style uses ulem package.

"cleveref"
Treat "\cref,\Cref", etc as equivalent to citation commands (i.e. protect with
"\mbox" if markup style uses ulem package.

"glossaries"
Define most of the glossaries commands as safe, protecting them with \mbox'es
where needed

"mhchem"
Treat "\ce" as a safe command, i.e. it will be highlighted (note that "\cee"
will not be highlighted in equations as this leads to processing errors)

"chemformula" or "chemmacros"
Treat "\ch" as a safe command outside equations, i.e. it will be highlighted
(note that "\ch" will not be highlighted in equations as this leads to
processing errors)

[ Default: scan the preamble for "\usepackage" commands to determine

--show-preamble
Print generated or included preamble commands to stdout.

Configuration
--exclude-safecmd=exclude-file or -A exclude-file or --exclude-safecmd="cmd1,cmd2,..."
--replace-safecmd=replace-file
--append-safecmd=append-file or -a append-file or --append-safecmd="cmd1,cmd2,..."
Exclude from, replace or append to the list of regular expressions (RegEx) matching
commands which are safe to use within the scope of a "\DIFadd" or "\DIFdel" command.
The file must contain one Perl-RegEx per line (Comment lines beginning with # or % are
ignored). Note that the RegEx needs to match the whole of the token, i.e., /^regex\$/
is implied and that the initial "\" of the command is not included. The
--exclude-safecmd and --append-safecmd options can be combined with the
---replace-safecmd option and can be used repeatedly to add cumulatively to the lists.
--exclude-safecmd and --append-safecmd can also take a comma separated list as input.
If a comma for one of the regex is required, escape it thus "\,". In most cases it
will be necessary to protect the comma-separated list from the shell by putting it in
quotation marks.

--exclude-textcmd=exclude-file or -X exclude-file or --exclude-textcmd="cmd1,cmd2,..."
--replace-textcmd=replace-file
--append-textcmd=append-file or -x append-file or --append-textcmd="cmd1,cmd2,..."
Exclude from, replace or append to the list of regular expressions matching commands
whose last argument is text. See entry for --exclude-safecmd directly above for
further details.

--replace-context1cmd=replace-file
--append-context1cmd=append-file or =item --append-context1cmd="cmd1,cmd2,..."
Replace or append to the list of regex matching commands whose last argument is text
but which require a particular context to work, e.g. \caption will only work within a
figure or table. These commands behave like text commands, except when they occur in
a deleted section, when they are disabled, but their argument is shown as deleted
text.

--replace-context2cmd=replace-file
--append-context2cmd=append-file or =item --append-context2cmd="cmd1,cmd2,..."
As corresponding commands for context1. The only difference is that context2 commands
are completely disabled in deleted sections, including their arguments.

--exclude-mboxsafecmd=exclude-file or --exclude-mboxsafecmd="cmd1,cmd2,..."
--append-mboxsafecmd=append-file or --append-mboxsafecmd="cmd1,cmd2,..."
Define safe commands, which additionally need to be protected by encapsulating in an
\\mbox{..}. This is sometimes needed to get around incompatibilities between external
packages and the ulem package, which is used for highlighting in the default style
UNDERLINE as well as CULINECHBAR CFONTSTRIKE

--config var1=val1,var2=val2,... or -c var1=val1,..
-c configfile
Set configuration variables. The option can be repeated to set different variables
(as an alternative to the comma-separated list). Available variables (see below for
further explanations):

"ARRENV" (RegEx)

"COUNTERCMD" (RegEx)

"FLOATENV" (RegEx)

"ITEMCMD" (RegEx)

"LISTENV" (RegEx)

"MATHARRENV" (RegEx)

"MATHARRREPL" (String)

"MATHENV" (RegEx)

"MATHREPL" (String)

"MINWORDSBLOCK" (integer)

"PICTUREENV" (RegEx)

--show-safecmd
Print list of RegEx matching and excluding safe commands.

--show-textcmd
Print list of RegEx matching and excluding commands with text argument.

--show-config
Show values of configuration variables.

--show-all
Combine all --show commands.

NB For all --show commands, no "old.tex" or "new.tex" file needs to be specified, and
no differencing takes place.

Other configuration options:
--allow-spaces
Allow spaces between bracketed or braced arguments to commands. Note that this option
might have undesirable side effects (unrelated scope might get lumpeded with preceding
commands) so should only be used if the default produces erroneous results. (Default
requires arguments to directly follow each other without intervening spaces).

--math-markup=level
Determine granularity of markup in displayed math environments: Possible values for
level are (both numerical and text labels are acceptable):

"off" or 0: suppress markup for math environments. Deleted equations will not appear
in diff file. This mode can be used if all the other modes cause invalid latex code.

"whole" or 1: Differencing on the level of whole equations. Even trivial changes to
equations cause the whole equation to be marked changed. This mode can be used if
processing in coarse or fine mode results in invalid latex code.

"coarse" or 2: Detect changes within equations marked up with a coarse granularity;
changes in equation type (e.g.displaymath to equation) appear as a change to the
complete equation. This mode is recommended for situations where the content and order
of some equations are still being changed. [Default]

"fine" or 3: Detect small change in equations and mark up at fine granularity. This
mode is most suitable, if only minor changes to equations are expected, e.g.
correction of typos.

--disable-citation-markup or --disable-auto-mbox
Suppress citation markup and markup of other vulnerable commands in styles using ulem
(UNDERLINE,FONTSTRIKE, CULINECHBAR) (the two options are identical and are simply
aliases)

--enable-citation-markup or --enforce-auto-mbox
Protect citation commands and other vulnerable commands in changed sections with
"\mbox" command, i.e. use default behaviour for ulem package for other packages (the
two options are identical and are simply aliases)

Miscellaneous
--verbose or -V
Output various status information to stderr during processing. Default is to work
silently.

--driver=type
Choose driver for changebar package (only relevant for styles using
changebar: CCHANGEBAR CFONTCHBAR CULINECHBAR CHANGEBAR). Possible drivers are
listed in changebar manual, e.g. pdftex,dvips,dvitops
[Default: dvips]

--ignore-warnings
Suppress warnings about inconsistencies in length between input and parsed strings and
missing characters. These warning messages are often related to non-standard latex or
latex constructions with a syntax unknown to "latexdiff" but the resulting difference
argument is often fully functional anyway, particularly if the non-standard latex only
occurs in parts of the text which have not changed.

--label=label or -L label
Sets the labels used to describe the old and new files. The first use of this option
sets the label describing the old file and the second use of the option sets the label
for the new file, i.e. set both labels like this "-L labelold -L labelnew". [Default:
use the filename and modification dates for the label]

--no-label
Suppress inclusion of old and new file names as comment in output file

--visble-label
Include old and new filenames (or labels set with "--label" option) as visible output.

--flatten
Replace "\input" and "\include" commands within body by the content of the files in
their argument. If "\includeonly" is present in the preamble, only those files are
expanded into the document. However, no recursion is done, i.e. "\input" and
"\include" commands within included sections are not expanded. The included files are
assumed to
be located in the same directories as the old and new master files, respectively,
making it possible to organise files into old and new directories. --flatten is
applied recursively, so inputted files can contain further "\input" statements.

Use of this option might result in prohibitive processing times for larger documents,
and the resulting difference document no longer reflects the structure of the input
documents.

--help or -h
Show help text

--version
Show version number

Predefined styles
Major types
The major type determine the markup of plain text and some selected latex commands outside
floats by defining the markup commands "\DIFadd{...}" and "\DIFdel{...}" .

"UNDERLINE"
Added text is wavy-underlined and blue, discarded text is struck out and red
(Requires color and ulem packages). Overstriking does not work in displayed
math equations such that deleted parts of equation are underlined, not struck
out (this is a shortcoming inherent to the ulem package).

Added text is blue and set in sans-serif, and a red footnote is created for each
discarded piece of text. (Requires color package)

Like "CTRADITIONAL" but without the use of color.

"CFONT" Added text is blue and set in sans-serif, and discarded text is red and very
small size.

"FONTSTRIKE"
Added tex is set in sans-serif, discarded text small and struck out

"CCHANGEBAR"
is marked with a bar in the margin (Requires color and changebar packages).

"CFONTCHBAR"
Like "CFONT" but with additional changebars (Requires color and changebar
packages).

"CULINECHBAR"
Like "UNDERLINE" but with additional changebars (Requires color, ulem and
changebar packages).

"CHANGEBAR"
No mark up of text, but mark margins with changebars (Requires changebar
package).

"INVISIBLE"
No visible markup (but generic markup commands will still be inserted.

"BOLD" Added text is set in bold face, discarded is not shown.

Subtypes
The subtype defines the commands that are inserted at the begin and end of added or
discarded blocks, irrespectively of whether these blocks contain text or commands (Defined

"SAFE" No additional markup (Recommended choice)

"MARGIN" Mark beginning and end of changed blocks with symbols in the margin nearby
(using the standard "\marginpar" command - note that this sometimes moves
somewhat from the intended position.

"COLOR" An alternative way of marking added passages in blue, and deleted ones in red.
(It is recommeneded to use instead the main types to effect colored markup,
although in some cases coloring with dvipscol can be more complete, for example
with citation commands).

"DVIPSCOL"
An alternative way of marking added passages in blue, and deleted ones in red.
Note that "DVIPSCOL" only works with the dvips converter, e.g. not pdflatex.
(it is recommeneded to use instead the main types to effect colored markup,
although in some cases coloring with dvipscol can be more complete).

"ZLABEL" can be used to highlight only changed pages, but requires post-processing. It is
recommend to not call this option manually but use "latexdiff-vc" with
"--only-changes" option. Alternatively, use the script given within preamble of
diff files made using this style.

"ONLYCHANGEDPAGE"
also highlights changed pages, without the need for post-processing, but might
not work reliably if there is floating material (figures, tables).

"LABEL" is similar to "ZLABEL", but does not need the zref package and works less
reliably (deprecated).

Float Types
Some of the markup used in the main text might cause problems when used within floats
(e.g. figures or tables). For this reason alternative versions of all markup commands are
used within floats. The float type defines these alternative commands.

"FLOATSAFE"
Use identical markup for text as in the main body, but set all commands marking
the begin and end of changed blocks to null-commands. You have to choose this
float type if your subtype is "MARGIN" as "\marginpar" does not work properly
within floats.

Mark additions the same way as in the main text. Deleted environments are
marked by angular brackets $and$ and the deleted text is set in scriptscript
size. This float type should always be used with the "TRADITIONAL" and
"CTRADITIONAL" markup types as the \footnote command does not work properly in
floating environments.

"IDENTICAL"
Make no difference between the main text and floats.

Configuration Variables
"ARRENV" If a match to "ARRENV" is found within an inline math environment within a
deleted or added block, then the inlined math is surrounded by "\mbox{"..."}".
This is necessary as underlining does not work within inlined array
environments.

[ Default: "ARRENV"="(?:array|[pbvBV]matrix)"

"COUNTERCMD"
If a command in a deleted block which is also in the textcmd list matches
cntcmd is the matching command, is appended in the diff file such that the
numbering in the diff file remains synchronized with the numbering in the new
file.

[ Default: "COUNTERCMD"="(?:footnote|part|section|subsection" ...

"|subsubsection|paragraph|subparagraph)" ]

"FLOATENV"
Environments whose name matches the regular expression in "FLOATENV" are
considered floats. Within these environments, the latexdiff markup commands are
replaced by their FL variaties.

[ Default: "(?:figure|table|plate)[\w\d*@]*" ]

"ITEMCMD" Commands representing new item line with list environments.

[ Default: \"item" ]

"LISTENV" Environments whose name matches the regular expression in "LISTENV" are list
environments.

[ Default: "(?:itemize|enumerate|description)" ]

"MATHENV","MATHREPL"
If both \begin and \end for a math environment (environment name matching
"MATHENV" or $and$) are within the same deleted block, they are replaced by
a \begin and \end commands for "MATHREPL" rather than being commented out.

[ Default: "MATHENV"="(?:displaymath|equation)" , "MATHREPL"="displaymath" ]

"MATHARRENV","MATHARRREPL"
as "MATHENV","MATHREPL" but for equation arrays

[ Default: "MATHARRENV"="eqnarray\*?" , "MATHREPL"="eqnarray" ]

"MINWORDSBLOCK"
Minimum number of tokens required to form an independent block. This value is
used in the algorithm to detect changes of complete blocks by merging identical
text parts of less than "MINWORDSBLOCK" to the preceding added and discarded
parts.

[ Default: 3 ]

"PICTUREENV"
Within environments whose name matches the regular expression in "PICTUREENV"
all latexdiff markup is removed (in pathologic cases this might lead to
inconsistent markup but this situation should be rare).

[ Default: "(?:picture|DIFnomarkup)[\w\d*@]*" ]

#### COMMONPROBLEMSANDFAQ

Citations result in overfull boxes
There is an incompatibility between the "ulem" package, which "latexdiff" uses
for underlining and striking out in the UNDERLINE style, the default style, and
the way citations are generated. In order to be able to mark up citations
properly, they are enclosed with an "\mbox" command. As mboxes cannot be broken
across lines, this procedure frequently results in overfull boxes, possibly
obscuring the content as it extends beyond the right margin. The same occurs
for some other packages (e.g., siunitx). If this is a problem, you have two
possibilities.

1. Use "CFONT" type markup (option "-t CFONT"): If this markup is chosen, then
changed citations are no longer marked up with the wavy line (additions) or
struck out (deletions), but are still highlighted in the appropriate color, and
deleted text is shown with a different font. Other styles not using the "ulem"
package will also work.

2. Choose option "--disable-citation-markup" which turns off the marking up of
citations: deleted citations are no longer shown, and added citations are shown
without markup. (This was the default behaviour of latexdiff at versions 0.6 and
older)

For custom packages you can define the commands which need to be protected by
"\mbox" with "--append-mboxsafecmd" and "--excludemboxsafecmd" options (submit
your lists of command as feature request at github page to set the default
behaviour of future versions, see section 6)

Changes in complicated mathematical equations result in latex processing errors
Try options "--math-markup=whole". If even that fails, you can turn off mark
up for equations with "--math-markup=off".

How can I just show the pages where changes had been made
Use options -"-s ZLABEL" (some postprocessing required) or "-s
ONLYCHANGEDPAGE". "latexdiff-vc --ps|--pdf" with "--only-changes" option takes
care of the post-processing for you (requires zref package to be installed).

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