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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 stan-
       dard input, executes them and prints the results on the  standard  out-
       put.   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 inter-
       preted 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  com-
       mand  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  char-
       acter  effectively removes that character, allowing to split long argu-
       ments 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 equiva-
              lent 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 cur-
              rently 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  argu-
              ments  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.


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 com-
       mand terminator, so each declaration can appear on a separate line  and
       arbitrary  number  of  comments can be inserted to document the defini-
       tion.

       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 for-
       mat 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 sim-
       plified 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  inter-
       preted to contain all bytes up to the end of the datum.


VARIABLES

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

       ps1, string
              Primary  prompt string.  Its value can contain conversion speci-
              fiers, consisting of the % character followed by another charac-
              ter.   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 (C) 2013-2021 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                            August 1, 2021                     gdbmtool(1)

gdbm 1.21 - Generated Sat Sep 11 07:54:27 CDT 2021
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