fhist(1)                    General Commands Manual                   fhist(1)

       fhist - file history

       fhist filename...  option...

       fhist -Help

       fhist -VERSion

       The fhist program is used to keep track of the successive versions of a
       file.  Using this program, you can remember all of your changes to a
       file, and get back any one of the old versions.  The uses of this
       ability are:

       1.  You can make a series of tentative edits to the file, and if
           necessary back up to the last "good" edit.

       2.  You can delete old subroutines and code from your file which are
           obsolete, but still be able to get them back in the future in case
           a need for them arises.

       3.  You can compare two versions of the file to see how you fixed some
           old problem, so that you can check up on the correctness of the fix
           at a later date.

       4.  You get a record of your remarks for each version, so that you can
           quickly know what bugs were fixed, and what features were

       5.  The date the file was last edited can be automatically stored in
           the file.

       The fhist program manipulates modules.  A module is simply any text
       file that you are interested in keeping versions of.  For example, a
       source file doit.c is a module, and so is a documentation file
       howto.doc.  The module name includes the suffix of the file (as in the
       above examples).  However, pathnames are not part of a module name, so
       that /usr/dbell/bar.c cannot be a legal module name.  A module name is
       limited to 12 characters since the fhist program needs two extra
       characters for its own purpose.

       The following options are understood:

       -Path pathname
               Modules are stored in a directory, called the module storage
               directory.  The default directory is FHIST, and therefore is
               located relative to your current directory.  This is convenient
               when you are in a directory containing many modules, and you
               want a local storage directory to contain just those modules.
               If you use the -p option, then you can locate the storage
               directory anywhere you choose.  This is useful if you choose to
               have a common storage directory for all of your files,
               independent of where they actually are used.

               The files inside of the storage directory should not be changed
               by you.  Doing so will probably corrupt your edit history,
               causing errors when you extract old revisions.  For your
               information, though, each module is stored as two files in the
               directory.  The one with the .s suffix is a copy of the newest
               version of the module, with one extra line at the beginning.
               The one with the .e suffix is the edit history of the module,
               and contains the information needed to extract previous
               revisions of the module.  Thus if the edit history is ever
               corrupted, you will at least have the most recent version of
               the module.

               To use the fhist program for the first time, you need to create
               your storage directory.  Therefore, cd to the directory where
               you want it to be, which is probably the directory containing
               the modules you want to save the revisions of.  Then create the
               directory FHIST (or some other name if you don't want to use
               the default name).

               To start using a module under fhist, you must first use the
               -CReate option.  This creates the initial edit for that module
               in the storage directory, with the contents of the specified
               module as the initial edit.  Thus, if you have a source file
               prog.c, then the command:
                      fhist prog.c -create
               creates the initial edit of the module.  As part of this
               process, you are asked to provide remarks about the file.
               These remarks can be seen later using the -List option
               (described below).  After the remarks have been typed, the
               contents of the file are then saved.  You can then delete the
               file prog.c if desired, and fhist would be able to recreate it
               later.  Or you can leave it there as the working copy of the

               The -CReate option may be combined with the -Update or
               -Conditional_Update options to create the file if required.

               To save another revision of the module, you use the -Update
               option.  This updates the files in the storage directory to
               include the latest changes.  Remarks are again asked for so
               that you can document why you made this edit.  Thus, to
               continue the example, after editing prog.c, the command:
                      fhist prog.c -u
               will save the changes as a new edit.  This command compares the
               newest version of the module to the previous version, saves the
               differences in the .e file, and copies the new source to the .s
               file.  At this point, you can once again delete the prog.c file
               if desired, and later get back either of the two versions of
               the program.

               The fhist program handles quota or disk full problems during a
               create or update operation without damage occurring to the edit
               history files.  If an edit cannot be completed because of such
               problems, the edit is backed out completely, and you will get
               an error message about the disk problem.  There is no need for
               any error recovery in this case, other than retrying the update
               when more disk space is available.  The fhist program also
               disables signals during the critical file operations, so you do
               not have to worry about damaging the edit history files because
               of attempts to quit out of the program.

               The -CReate option may be combined with the -Update or
               -Conditional_Update options to create the file if required.

       -Input filename
               In either the -CReate or -Update options, the file containing
               the new version of the module defaults to the same name as the
               module.  In the example, the module prog.c was created and
               updated from the data in the file prog.c.  When you wish the
               data to come from some other file, you can use the -Input
               option, which specifies the input file to use for the data.
               For example, if you wanted to update prog.c, but from a
               filename called newprog.c, then the command:
                      fhist prog.c -u -i newprog.c
               would save a new revision of module prog.c, but with the data
               that was in the file newprog.c.  In this case, the file prog.c
               does not have to exist, and isn't referenced even if it did
               exist.  Again, once the update is complete, you could delete
               the newprog.c file if desired and then later you can retrieve
               its contents.

               Remarks can be read from a file instead of from the terminal.
               The -Remarks option can be used to specify a file name
               containing the remarks.  If there is no file name following the
               -Remarks option, then no remarks at all are used.  The command:
                      fhist prog.c -u -r
               would create a new revision of prog.c without asking for or
               saving any remarks about the edit.

       -Extract [ edit ]
               To retrieve a previous revision of a module, you specify the
               name of the module and use the -Extract option to specify the
               edit number you want retrieved.  Edit numbers are assigned
               sequentially starting with 1.  Thus the initial version of the
               module has edit number 1, the first revision has edit number 2,
               and so on until the latest revision.  If the -Extract option is
               not used, or if no edit number is supplied for it, then the
               latest edit number is extracted.  Therefore, this is the
               default action if no options at all are specified.

               Edit numbers can also be zero, negative, or be a name with an
               optional offset.  The number zero represents the latest edit
               number, and negative numbers indicate edit numbers backwards
               from the latest edit number.  Edit names represent edit numbers
               whose name had been set by using the -Name option.  For
               example, if edit number 10 was associated with the name foo,
               then the edit name foo represents 10, foo-4 represents edit
               number6, and foo+2 represents edit number 12.  The special
               reserved names oldest and newest refer to the oldest and newest
               versions of the module in the edit history.

               As an example of retrievals, assume that you have saved ten
               versions of the module prog.c.  The following commands will
               then extract the versions of the file with the specified edit

               fhist prog.c
                       version 10 (the latest)

               fhist prog.c -e 9
                       version 9 (the version just prior)

               fhist prog.c -e oldest
                       version 1 (the oldest version)

               fhist prog.c -e -2
                       version 8 (latest version - 2)

               The output filename is again defaulted to the module name.  So
               when the module prog.c is extracted, the specified version of
               the module is written to the prog.c file.

               In order to prevent accidental overwriting of a file, the fhist
               program will by default ask you if overwriting is permitted if
               that would occur.  A common mistake is to edit prog.c, and then
               try to update the module, but forget to specify the -u option.
               Then the fhist program would try to extract the newest version
               of the module, and thus overwrite the file with the new
               changes.  Asking the question allows you to notice your
               mistake, and prevent the overwriting.

       -Output filename
               You can change the output filename using the -Output option.
               Thus, the command:
                      fhist prog.c -o newprog.c
               will extract the latest version of the module prog.c, and put
               it into the file newprog.c.  Once again, the file "prog.c" is
               ignored, whether or not it existed.

               This option will force overwriting of the file, thus never
               asking you if overwriting is permitted.  This is often useful
               in shell scripts, or when you are sure that you want to
               overwrite any existing file.

               This option is the no-overwrite option, and will cause any
               existing files to not be overwritten, again without asking you.
               This is useful if you already have some of the modules in your
               directory, and you want to extract the rest of the modules
               without overwriting the ones you already have.  Specifying both
               -Fore_Write and -No_Write is an error.

       -Terminal [ edit ]
               This option is used to output an extracted module to the
               standard output, instead of writing it to a file.  This is
               useful in order to view the beginning of a version of the file.
               This can be interrupted if you do not want to see the whole

       -Modify number
               When extracting a file, the fhist program looks for and updates
               special character sequences in the first few lines of the file.
               These special sequences are used for documentation purposes,
               such as describing the edit number the file is from.  For speed
               of extraction and updating, these sequences are usually limited
               to the first 25 lines of the file, since the fhist program then
               does not have to examine the entire file.  The -Modify option
               can be used to change the number of lines to be modified from
               the default value of 25.  Specifying zero totally disables the
               special character sequences, whereas specifying a very large
               number will cause the sequences to be checked for each line of
               the file (and thus slow the fhist program down).

               Each special sequence is of the form [# keyword value, keyword
               value, ..., keyword value #] , where each keyword describes an
               item, and each value is the value for the preceding keyword.
               The keywords can be in upper or lower case, or both.  The
               single space following the [#, following each comma, and
               preceding the #] must be present.  If the sequence is wrong, an
               unknown keyword is used, the line is longer than 200
               characters, or more than four keywords are used, then the whole
               line will not be changed.  The current keywords which can be
               used are the following:

               edit    The edit number

               date    The date that the edit was created

               user    The user name of the user who created the edit

               module  The module name

               In order to use this special character sequence, you simply
               insert it into your module inside of a comment (within the
               first few lines).  When this is done, the value parts of the
               sequence can be null.  For example, if you want to put a
               special sequence into a program called delete.c, then you could
               edit the first few lines as follows:
                       * Delete - program to delete files
                       * [# Edit, Date #]
               When an extract is done, the proper edit number and date are
               automatically inserted as the new values.  Thus, if you extract
               edit 23 of the module delete.c which had been created on 8
               August 89, then the resulting file would begin:
                       * Delete - program to delete files
                       * [# Edit 23, Date 8-Aug-89 #]

               When updating a module, it is never necessary to edit these
               sequences, as any old values will be removed and replaced with
               the new ones.  Also, when using the -d or -du options
               (described below), lines with these sequences compare as if the
               values were null, and thus will not cause spurious differences.

               During an update, the special character sequences are read and
               any edit value found is compared against the current edit
               number of the module.  If they differ, then the update fails.
               This provides an interlock check for the case of two users
               extracting the same version of a file, editing it, and then
               both updating it without knowledge of each other.  In this
               case, the second user would fail, and then he can merge his
               edits with the previous user's edit and then retry the update.
               This checking is disabled if there is no special character
               sequence containing the edit keyword, the edit number value is
               null, or if the -Forced_Update option is used to indicate that
               the check is not needed.

       -Name string
               This option is used to associate a name for the newest version
               of a module.  It can be given along with the -CReate, -Update,
               or -Difference_Update options, to specify a name for the new
               version of the module.  It can also be given by itself in order
               to specify a name for the newest version of a module.  Each
               edit number can have many names associated with it, so this
               will not remove any previously defined name for the edit.  This
               option is useful to correlate many modules together.  For
               example, when a new version of a program is ready to be
               released, you could give each module of the program the same
               name release1.  Then in the future, you can recreate the
               sources making up that release by extracting the edits with the
               name release1 for every module.  Edit names cannot begin with a
               digit, and cannot contain plus or minus signs.  These rules
               prevent ambiguous parsing of edit numbers for the -Extract,
               -Terminal, -ALL, and -List options.

       -List [ edit1 [ edit2 ]]
               This option prints a list of edits for the module, giving the
               user name, date, user remarks, and names specified for the
               edits.  If no edit number is supplied, then all edits are
               printed in reverse order.  If a single edit number is supplied,
               then only that edit number is printed.  If two edit numbers are
               supplied, then all edits in the specified range are printed.
               The output from this option defaults to the terminal.  You can
               use the -Output option to save the results to a file.

       -Difference [ edit1 [ edit2 ]]
               This option is used to display the differences between two
               versions of a module, or a file and a version of a module.
               There are three modes for this action, depending on how many
               edit numbers are supplied.  These modes are illustrated by the
               following examples:

               fhist foo.c -d
                       Compare latest version against file "foo.c"

               fhist foo.c -d 3
                       Compare version 3 against file "foo.c"

               fhist foo.c -d 3 4
                       Compare version 3 against version 4

               This option accepts the -Input option to specify the file to be
               compared.  When using the -Difference option, the output
               defaults to the terminal.  Therefore, you must use -Output if
               you wish the differences saved to a file.  Using -Quick with
               -Difference will only output a quick summary of the changes,
               instead of the detailed changes.  This summary only supplies
               the number of lines inserted, deleted, and unchanged between
               the files.  Using -What with -Difference will display all of
               both files, showing in detail what the differences are using
               change bars.

               The -Difference option may need to write one or two temporary
               files in order to extract old versions of a module to be
               compared.  These files have names like T$n_nnn .  They are
               deleted again just before differences are output, so that
               stopping the output before it is complete will not leave these
               files around.  The temporary files are usually written to the
               current directory.  If this is not reasonable because of
               permission or quota problems, then you can specify the
               directory for writing the temporary files into.  This is done
               by defining the TMPDIR environment variable to be the path of
               the directory.

               This option combines the effects of the -Difference and -Update
               options.  It displays the differences between a file and the
               latest version of a module.  If there are any differences, it
               then proceeds to perform an update of the module with that
               file, asking for remarks as usual.  This option is very useful
               when used with wildcarded module names.  Then you can update
               just those modules which were changed by an edit session, and
               see the changes for each module before typing the appropriate
               remark for each module.

               You may specify both of the -Difference and -Update options, or
               you may use this option.  The results are identical.

               This option conditionally updates a module.  That is, it will
               only do an update if there are any differences between a file
               and the latest version of a module.  This is convenient when
               related changes are made to many modules in a directory, and
               one command using wildcards can update just those modules that
               were changed.

               The -CReate option may be combined with the -Update or
               -Conditional_Update options to create the file if required.

               This option is used to remove files which match the newest
               versions of modules.  If a file exists which matches the newest
               version of a module, then the file is deleted, otherwise it is
               kept.  This option is used to clean up a work directory after
               building a new version of a product.  This option is especially
               useful when used with the -ALL option.  It will also accept the
               -Input option to specify a directory containing the files to be

               This option is used to find out if a file does not match the
               latest version of a module.  If so, a message is given.  If the
               file does match, no output occurs.  This option is thus useful
               to determine which files have been modified and in need of
               updating.  The -ALL option is defaulted for this option, since
               it is usually used for all modules.  For example,
                      fhist -CHeck
               will report on all files which are different than the latest
               modules.  If -Quick is specified, then the output will consist
               of the module names with no other output.  This is useful for
               the backquote operator in shell scripts for referencing the
               modules which are out of date.  The -CHeck option will also
               accept the -Input option.

       -PRune edit
               This option is used to permanently remove early edits from an
               edit history.  This is useful if you wish to cut down on the
               amount of disk space taken by an edit history file, or when you
               want to start another release of a file, and want a copy of the
               edit history file for that new release.  The option takes an
               edit number to preserve, and all edits in the edit history file
               before that edit are deleted, and can no longer be referenced.
               For example, to keep only the current edit plus the previous 10
               edits of the module file, you could use the command:
                      fhist file -prune -10
               Since the -PRune option is unrecoverable (unless backup files
               are available), the fhist program asks the user to verify that
               the prune is really wanted.  The -Forced_Update option can be
               used to bypass this verification.

               This option can be used with any of the action options.  It
               means perform the operation for all modules in the module
               storage directory.  Alternatively, you can specify multiple
               module names on the command line, and the actions will be
               performed with those modules.  You cannot specify both -ALL and
               module names.

               When using multiple modules or the -ALL option, the -Input and
               -Output options have a slightly different meaning.  In these
               cases, the -Input and -Output arguments are a directory name
               which contains filenames with the same name as the module
               names.  If the argument is not a directory, then an error is
               given.  This feature is useful for example, to extract all the
               modules and place them into some remote directory, as in:
                      fhist -all -e -o tempdir

               You should be careful when specifying numeric edit numbers for
               multiple modules.  Most probably, a particular edit number is
               not appropriate for multiple modules, since changes
               corresponding to a particular edit number are not usually
               related.  Using named edits avoids these problems.  As an
               example, if you wanted to extract every module which had an
               edit that was named rev3, then you could use the command:
                      fhist -all -e rev3

               Some other useful examples of commands which use multiple
               modules are:
                      fhist *.c -create
                      fhist -check -all
                      fhist -cu -all

               This option can be specified with any other action, and outputs
               status information about the progress of the action.  This is
               useful for debugging of problems, or just for amusement when
               the system is slow or a large file is being processed.  It
               accepts a numeric argument to indicate the verbosity for
               output.  The levels are as follows:

               0   No output at all (except for errors).

               1   Single-line output describing action (default).

               2   Detailed status as action proceeds.

               Give some help on how to use the fhist program.

               Show what version of fhist is running.

       All options may be abbreviated; the abbreviation is documented as the
       upper case letters, all lower case letters and underscores (_) are
       optional.  You must use consecutive sequences of optional letters.

       All options are case insensitive, you may type them in upper case or
       lower case or a combination of both, case is not important.

       For example: the arguments "-help, "-HELP" and "-h" are all interpreted
       to mean the -Help option.  The argument "-hlp" will not be understood,
       because consecutive optional characters were not supplied.

       Options and other command line arguments may be mixed arbitrarily on
       the command line.

       The GNU long option names are understood.  Since all option names for
       fhist are long, this means ignoring the extra leading '-'.  The
       "--option=value" convention is also understood.

       As a convenience, if a pathname begins with a period and a environment
       variable exists with that name, then the value of the environment
       variable will be used as the actual pathname.  For example, if a
       environment variable of .FOO has the value this.is.a.long.name, then
       the command
              fhist -o .FOO
       is actually equivilant to the command
              fhist -o this.is.a.long.name
       If you want to prevent the expansion of a pathname which begins with a
       period, then you can use an alternate form for the pathname, as in:
              fhist -o ./.FOO

       In general, fhist can handle all text files you throw at it, even
       international text with unusual encodings.  However, fhist is unable to
       cope elegantly with files which contain the NUL character.

       The fcomp(1) program simply prints a warning, and continues, you need
       to know that it converts NUL characters into an 0x80 value before
       performing the comparison.

       The fmerge(1) program also converts the NUL character to an 0x80 value
       before merging, after a warning, and any output file will contain this
       value, rather than the original NUL character.

       The fhist(1) program, however, generates a fatal error if any input
       file contains NUL characters.  This is intended to protect your source
       files for unintentional corruption.  Use uuencode for files which
       absolutely must contain NUL characters.

       The fhist program will exit with a status of 1 on any error.  The fhist
       program will only exit with a status of 0 if there are no errors.

       This program is based on the algorithm in
              An O(ND) Difference Algorithm and Its Variations, Eugene W.
              Myers, TR 85-6, 10-April-1985, Department of Computer Science,
              The University of Arizona, Tuscon, Arizona 85721.
       See also:
              A File Comparison Program, Webb Miller and Eugene W. Myers,
              Software Practice and Experience, Volume 15, No. 11, November

       fhist version 1.6.D001
       Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999
       Peter Miller; All rights reserved.

       This program is derived from a work
       Copyright (C) 1990 David I. Bell.

       This program is free software; you can redistribute it and/or modify it
       under the terms of the GNU General Public License as published by the
       Free Software Foundation; either version 2 of the License, or (at your
       option) any later version.

       This program is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       General Public License for more details.

       You should have received a copy of the GNU General Public License along
       with this program; if not, write to the Free Software Foundation, Inc.,
       59 Temple Place, Suite 330, Boston, MA 02111, USA.

       Peter Miller         Web:   http://www.canb.auug.org.au/~millerp
       /\/\*             E-Mail:   millerp@canb.auug.org.au

       David I. Bell        Web:   uhttp://www.canb.auug.org.au/~dbell
                       Internet:   dbell@canb.auug.org.au

Reference Manual                     FHist                            fhist(1)