GDBMTOOL(1)		      GDBM User Reference		   GDBMTOOL(1)

NAME
       gdbmtool - examine and modify a GDBM database

SYNOPSIS
       gdbmtool [-lmNnqrs] [-b SIZE] [-c SIZE] [-f FILE] [--block-size=SIZE]
       [--cache-size=SIZE] [--file FILE] [--newdb] [--no-lock] [--no-mmap]
       [--norc] [--quiet] [--read-only] [--synchronize] [DBFILE] [COMMAND [;
       COMMAND...]]

       gdbmtool [-Vh] [--help] [--usage] [--version]

DESCRIPTION
       The gdbmtool utility allows you to view and modify an existing GDBM
       database or to create a new one.

       The DBFILE argument supplies the name of the database to open.  If not
       supplied, the default name junk.gdbm is used instead.  If the named
       database does not exist, it will be created.  An existing database can
       be cleared (i.e. all records removed from it) using the --newdb option
       (see below).

       Unless the -N (--norc) option is given, after startup gdbmtool looks
       for file named .gdbmtoolrc first in the current working directory, and,
       if not found there, in the home directory of the user who started the
       program.	 If found, this file is read and interpreted as a list of
       gdbmtool commands.

       Then gdbmtool starts a loop, in which it reads commands from the
       standard input, executes them and prints the results on the standard
       output.	If the standard input is attached to a console, the program
       runs in interactive mode.

       The program terminates when the quit command is given, or end-of-file
       is detected on its standard input.

       Commands can also be specified in the command line, after the DBFILE
       argument. In this case, they will be interpreted without attempting to
       read more commands from the standard input.

       If several commands are supplied, they must be separated by semicolons
       (properly escaped or quoted, in order to prevent them from being
       interpreted by the shell).

       A gdbmtool command consists of a command verb, optionally followed by
       one or more arguments, separated by any amount of white space.  A
       command verb can be entered either in full or in an abbreviated form,
       as long as that abbreviation does not match any other verb.

       Any sequence of non-whitespace characters appearing after the command
       verb forms an argument.	If the argument contains whitespace or
       unprintable characters it must be enclosed in double quotes.  Within
       double quotes the usual escape sequences are understood, as shown in
       the table below:

	       Escape	   Expansion
	       \a	   Audible bell character (ASCII 7)
	       \b	   Backspace character (ASCII 8)
	       \f	   Form-feed character (ASCII 12)
	       \n	   Newline character (ASCII 10)
	       \r	   Carriage return character (ASCII 13)
	       \t	   Horizontal tabulation character (ASCII 9)
	       \v	   Vertical tabulation character (ASCII 11)
	       \\	   Single slash


       In addition, a backslash immediately followed by the end-of-line
       character effectively removes that character, allowing to split long
       arguments over several input lines.

OPTIONS
       -b, --block-size=SIZE
	      Set block size.

       -c, --cache-size=SIZE
	      Set cache size.

       -f, --file=FILE
	      Read commands from FILE, instead of from the standard input.

       -l, --no-lock
	      Disable file locking.

       -m, --no-mmap
	      Do not use mmap(2).

       -n, --newdb
	      Create the database, truncating it if it already exists.

       -q, --quiet
	      Don't print initial banner.

       -r, --read-only
	      Open database in read-only mode.

       -s, --synchronize
	      Synchronize to disk after each write.

       -h, --help
	      Print a short usage summary.

       --usage
	      Print a list of available options.

       -V, --version
	      Print program version

SHELL COMMANDS
       avail  Print the avail list.

       bucket NUM
	      Print the bucket number NUM and set is as the current one.

       cache  Print the bucket cache.

       close  Close the currently open database.

       count  Print the number of entries in the database.

       current
	      Print the current bucket.

       delete KEY
	      Delete record with the given KEY.

       dir    Print hash directory.

       downgrade
	      Downgrade the database from the extended numsync format to the
	      standard format.

       export FILE-NAME [truncate] [binary|ascii]
	      Export the database to the flat file FILE-NAME.  This is
	      equivalent to gdbm_dump(1).

	      This command will not overwrite an existing file, unless the
	      truncate parameter is also given.	 Another optional parameter
	      determines the type of the dump (*note Flat files::).  By
	      default, ASCII dump will be created.

       fetch KEY
	      Fetch and display the record with the given KEY.

       first  Fetch and display the first record in the database.  Subsequent
	      records can be fetched using the next command (see below).

       hash KEY
	      Compute and display the hash value for the given KEY.

       header Print file header.

       help or ?
	      Print a concise command summary, showing each command letter and
	      verb with its parameters and a short description of what it
	      does.  Optional arguments are enclosed in square brackets.

       history
	      Shows the command history list with line numbers.	 This command
	      is available only if the program was compiled with GNU Readline.

       history COUNT.
	      Shows COUNT latest commands from the command history.

       history N COUNT.
	      Shows COUNT commands from the command history starting with Nth
	      command.

       import FILE-NAME [replace] [nometa]
	      Import data from a flat dump file FILE-NAME.  If the replace
	      argument is given, any records with the same keys as the already
	      existing ones will replace them.	The nometa argument turns off
	      restoring meta-information from the dump file.

       list   List the contents of the database.

       next [KEY]
	      Sequential access: fetch and display the next record.  If the
	      KEY is given, the record following the one with this key will be
	      fetched.

       open FILE
	      Open the database file FILE.  If successful, any previously open
	      database is closed.  Otherwise, if the operation fails, the
	      currently opened database remains unchanged.

	      This command takes additional information from the variables
	      open, lock, mmap, and sync.  See the section VARIABLES, for a
	      detailed description of these.

       quit   Close the database and quit the utility.

       reorganize
	      Reorganize the database.

       set [VAR=VALUE...]
	      Without arguments, lists variables and their values.  If
	      arguments are specified, sets variables.	 Boolean variables can
	      be set by specifying variable name, optionally prefixed with no,
	      to set it to false.

       snapshot FILE FILE
	      Analyzes two database snapshots and selects the most recent of
	      them.  In case of error, prints a detailed diagnostics.  Use
	      this command to manually recover from a crash.  For details,
	      please refer to the chapter Crash Tolerance in the GDBM manual.

       source FILE
	      Read commands from the given FILE.

       status Print current program status.

       store KEY DATA
	      Store the DATA with the given KEY in the database.  If the KEY
	      already exists, its data will be replaced.

       sync   Synchronize the database file with the disk storage.

       upgrade
	      Upgrade the database from the standard to the extended numsync
	      format.

       unset VARIABLE...
	      Unsets listed variables.

       version
	      Print the version of gdbm.

PIPES
       A command can be followed by a pipe sign (|) and a shell command.  The
       meaning is the same as in Bourne shell: the output of the gdbmtool
       command is connected to the input of a shell command specified on the
       right side of |.	 In this case pager is disabled.

DATA DEFINITIONS
       The define statement provides a mechanism for defining key or content
       structures.  It is similar to the C struct declaration:

	   define key|content { defnlist }

       The defnlist is a comma-separated list of member declarations.  Within
       defnlist the newline character looses its special meaning as the
       command terminator, so each declaration can appear on a separate line
       and arbitrary number of comments can be inserted to document the
       definition.

       Each declaration has one of the following formats

	   type name
	   type name [N]

       where type is a data type and name is the member name.  The second
       format defines the member name as an array of N elements of type.

       The supported types are:

	       type	   meaning
	       char	   single byte (signed)
	       short	   signed short integer
	       ushort	   unsigned short integer
	       int	   signed integer
	       unsigned	   unsigned integer
	       uint	   ditto
	       long	   signed long integer
	       ulong	   unsigned long integer
	       llong	   signed long long integer
	       ullong	   unsigned long long integer
	       float	   a floating point number
	       double	   double-precision floating point number
	       string	   array of characters (see the NOTE below)
	       stringz	   null-terminated string of characters

       The following alignment declarations can be used within defnlist:

       offset N
	      The next member begins at offset N.

       pad N  Add N bytes of padding to the previous member.

       For example:

	   define content {
		   int status,
		   pad 8,
		   char id[3],
		   stringz name
	   }

       To define data consisting of a single data member, the following
       simplified construct can be used:

	   define key|content type

       where type is one of the types discussed above.

       NOTE: The string type can reasonably be used only if it is the last or
       the only member of the data structure.  That's because it provides no
       information about the number of elements in the array, so it is
       interpreted to contain all bytes up to the end of the datum.

VARIABLES
       confirm, boolean
	      Whether to ask for confirmation before certain destructive
	      operations, such as truncating the existing database.  Default
	      is true.

       ps1, string
	      Primary prompt string.  Its value can contain conversion
	      specifiers, consisting of the % character followed by another
	      character.  These specifiers are expanded in the resulting
	      prompt as follows:

		      Sequence	  Expansion
		      %f	  name of the db file
		      %p	  program name
		      %P	  package name (gdbm)
		      %_	  horizontal space (ASCII 32)
		      %v	  program version
		      %%	  %

	      The default prompt is %p>%_.

       ps2, string
	      Secondary prompt.	 See ps1 for a description of its value.  This
	      prompt is displayed before reading the second and subsequent
	      lines of a multi-line command.

	      The default value is %_>%_.

       delim1, string
	      A string used to delimit fields of a structured datum on output
	      (see the section DATA DEFINITIONS).

	      Default is , (a comma).  This variable cannot be unset.

       delim2, string
	      A string used to delimit array items when printing a structured
	      datum.

	      Default is , (a comma).  This variable cannot be unset.

       pager, string
	      The name and command line of the pager program to pipe output
	      to.  This program is used in interactive mode when the estimated
	      number of output lines is greater then the number of lines on
	      your screen.

	      The default value is inherited from the environment variable
	      PAGER.  Unsetting this variable disables paging.

       quiet, boolean
	      Whether to display welcome banner at startup.  This variable
	      should be set in a startup script file.

       The following variables control how the database is opened:

       cachesize, numeric
	      Sets the cache size.  By default this variable is not set.

       blocksize, numeric
	      Sets the block size.  Unset by default.

       open, string
	      Open mode.  The following values are allowed:

	      newdb  Truncate the database if it exists or create a new one.
		     Open it in read-write mode.

	      wrcreat or rw
		     Open the database in read-write mode.  Create it if it
		     does not exist.  This is the default.

	      reader or readonly
		     Open the database in read-only mode.  Signal an error if
		     it does not exist.

       filemode, octal
	      Sets the file mode for newly created database files. Default is
	      0644.

       lock, boolean
	      Lock the database.  This is the default.

       mmap, boolean
	      Use memory mapping.  This is the default.

       coalesce, boolean
	      When set, this option causes adjacent free blocks to be merged
	      which allows for more efficient memory management at the expense
	      of a certain increase in CPU usage.

       centfree, boolean
	      Enables central free block pool. This causes all free blocks of
	      space to be placed in the global pool, thereby speeding up the
	      allocation of data space.

SEE ALSO
       gdbm_dump(1), gdbm_load(1), gdbm(3).

REPORTING BUGS
       Report bugs to <bug-gdbm@gnu.org>.

COPYRIGHT
       Copyright © 2013-2025 Free Software Foundation, Inc
       License GPLv3+: GNU GPL version 3 or later
       <http://gnu.org/licenses/gpl.html>
       This is free software: you are free to change and redistribute it.
       There is NO WARRANTY, to the extent permitted by law.

GDBM				 March 6, 2025			   GDBMTOOL(1)