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NDBM_File (3)
NDBM_File (3) ( Solaris man: Библиотечные вызовы )
>> NDBM_File (3) ( Разные man: Библиотечные вызовы )
NAME
NDBM_File - Tied access to ndbm files
SYNOPSIS
use Fcntl; # For O_RDWR, O_CREAT, etc.
use NDBM_File;
tie(%h, 'NDBM_File', 'filename', O_RDWR|O_CREAT, 0666)
or die "Couldn't tie NDBM file 'filename': $!; aborting";
# Now read and change the hash
$h{newkey} = newvalue;
print $h{oldkey};
...
untie %h;
DESCRIPTION
"NDBM_File" establishes a connection between a Perl hash variable and
a file in NDBM_File format;. You can manipulate the data in the file
just as if it were in a Perl hash, but when your program exits, the
data will remain in the file, to be used the next time your program
runs.
Use "NDBM_File" with the Perl built-in "tie" function to establish
the connection between the variable and the file. The arguments to
"tie" should be:
1.
The hash variable you want to tie.
2.
The string "NDBM_File". (Ths tells Perl to use the "NDBM_File"
package to perform the functions of the hash.)
3.
The name of the file you want to tie to the hash.
4.
Flags. Use one of:
O_RDONLY
Read-only access to the data in the file.
O_WRONLY
Write-only access to the data in the file.
O_RDWR
Both read and write access.
If you want to create the file if it does not exist, add "O_CREAT" to
any of these, as in the example. If you omit "O_CREAT" and the file
does not already exist, the "tie" call will fail.
5.
The default permissions to use if a new file is created. The actual
permissions will be modified by the user's umask, so you should
probably use 0666 here. (See ``umask'' in perlfunc.)
DIAGNOSTICS
On failure, the "tie" call returns an undefined value and probably
sets $! to contain the reason the file could not be tied.
ndbm store returned -1, errno 22, key ... at ...
This warning is emitted when you try to store a key or a value that
is too long. It means that the change was not recorded in the
database. See BUGS AND WARNINGS below.
BUGS AND WARNINGS
There are a number of limits on the size of the data that you can
store in the NDBM file. The most important is that the length of a
key, plus the length of its associated value, may not exceed 1008
bytes.
