gdbmtool(1)
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]
gdbmtool [-Vh] ][--help] [--usage] [--version]
DESCRIPTION
The gdbmtool utility allows you to view and modify an exist-
ing 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.
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 con-
tains 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:
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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, allow-
ing 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
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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.
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 com-
mand (see below).
hash KEY
Compute and display the hash value for the given KEY.
header
Print file header.
help or ?
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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 previ-
ously 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.
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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.
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 declara-
tions. Within defnlist the newline character looses its
special meaning as the command terminator, so each declara-
tion 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 ele-
ments 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
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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 fol-
lowing 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 ele-
ments 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 destruc-
tive operations, such as truncating the existing data-
base. Default is true.
ps1, string
Primary prompt string. Its value can contain conver-
sion 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)
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%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 pag-
ing.
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
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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.
lock, boolean
Lock the database. This is the default.
mmap, boolean
Use memory mapping. This is the default.
SEE ALSO
gdbm_dump(1), gdbm_load(1), gdbm(3).
REPORTING BUGS
Report bugs to <bug-gdbm@gnu.org>.
COPYRIGHT
Copyright 8c9 2013 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 redistri-
bute it. There is NO WARRANTY, to the extent permitted by
law.
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