MAN page from Fedora 26 gdbm-1.13-1.fc26.x86_64.rpm


Section: GDBM User Reference (1)
Updated: July 12, 2016


gdbmtool - examine and modify a GDBM database 


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]

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


Thegdbmtoolutility allows you to view and modify an existing GDBM database or tocreate a new one.

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

Unless the -N (--norc) option is given, after startupgdbmtoollooks for file named.gdbmtoolrcfirst in the current working directory, and, if not found there, inthe home directory of the user who started the program. If found,this file is read and interpreted as a list ofgdbmtoolcommands.

Thengdbmtoolstarts a loop, in which it readscommands from the standard input, executes them and prints the results on thestandard output. If the standard input is attached to a console,the program runs in interactive mode.

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

Agdbmtoolcommand consists of a command verb, optionallyfollowed by one or more arguments, separated by any amount of whitespace. A command verb can be entered either in full or in anabbreviated form, as long as that abbreviation does not match any otherverb.

Any sequence of non-whitespace characters appearing after the commandverb forms an argument. If the argument contains whitespace orunprintable characters it must be enclosed in double quotes. Withindouble quotes the usual escape sequences are understood, asshown 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 longarguments over several input lines. 


-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 usemmap(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.
Print a list of available options.
-V, --version
Print program version


Print the avail list.
bucket NUM
Print the bucket number NUM and set is as the current one.
Print the bucket cache.
Close the currently open database.
Print the number of entries in the database.
Print the current bucket.
delete KEY
Delete record with the given KEY.
Print hash directory.
export FILE-NAME [truncate] [binary|ascii]
Export the database to the flat file FILE-NAME. This is equivalent togdbm_dump(1).

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

fetch KEY
Fetch and display the record with the given KEY.
Fetch and display the first record in the database. Subsequentrecords can be fetched using thenextcommand (see below).
hash KEY
Compute and display the hash value for the given KEY.
Print file header.
help or ?
Print a concise command summary, showing each command letter andverb with its parameters and a short description of what it does.Optional arguments are enclosed in square brackets.
Shows the command history list with line numbers. This command isavailable 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 Nthcommand.
import FILE-NAME [replace] [nometa]
Import data from a flat dump file FILE-NAME.If thereplaceargument is given, any records with the same keys as the alreadyexisting ones will replace them. Thenometaargument turns off restoring meta-information from the dump file.
List the contents of the database.
next [KEY]
Sequential access: fetch and display the next record. If the KEY isgiven, the record following the one with this key will be fetched.
open FILE
Open the database file FILE. If successful, any previouslyopen database is closed. Otherwise, if the operation fails, thecurrently opened database remains unchanged.

This command takes additional information from the variablesopen,lock,mmap, andsync.See the sectionVARIABLES,for a detailed description of these.

Close the database and quit the utility.
Reorganize the database.
set [VAR=VALUE...]
Without arguments, lists variables and their values. If arguments arespecified, sets variables. Boolean variables can be set by specifyingvariable name, optionally prefixed with no, to set it to false.
source FILE
Read commands from the given FILE.
Print current program status.
store KEY DATA
Store the DATA with the given KEY in the database. If theKEY already exists, its data will be replaced.
unset VARIABLE...
Unsets listed variables.
Print the version ofgdbm.


The define statement provides a mechanism for defining key orcontent structures. It is similar to the C structdeclaration:

define key|content { defnlist }

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

Each declaration has one of the following formats

type nametype 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 Nelements 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 followingsimplified 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 isthe last or the only member of the data structure. That's because itprovides no information about the number of elements in the array, soit is interpreted to contain all bytes up to the end of the datum. 


confirm, boolean
Whether to ask for confirmation before certain destructive operations,such as truncating the existing database. Default istrue.
ps1, string
Primary prompt string. Its value can contain conversionspecifiers, consisting of the % character followed by anothercharacter. These specifiers are expanded in the resulting prompt asfollows:

        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. Seeps1for a description of its value.This prompt is displayed before reading the second and subsequentlines 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 ofoutput lines is greater then the number of lines on your screen.

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

quiet, boolean
Whether to display welcome banner at startup. This variable shouldbe 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:
Truncate the database if it exists or create a new one. Open it inread-write mode.
wrcreat or rw
Open the database in read-write mode. Create it if it does notexist. This is the default.
reader or readonly
Open the database in read-only mode. Signal an error if it does notexist.
lock, boolean
Lock the database. This is the default.
mmap, boolean
Use memory mapping. This is the default.





Report bugs to <>. 


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




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