Dean Theophilou wrote:
>
> Hello All:
>
> I was wondering if there is any way to create an environment variable under
> UNIX which can be used as a persistent counter. Can this be done, or you
> limited to whatever environment variables already exist within a system?
> Also, is there an easy way to query environment variables under UNIX like
> there is with Win32 (through the AdminMisc module)? Thanks.
Something like mod_perl or a shared memory module should do the trick.
Otherwise just use a file and flock. Not sure if your UNIX supports it or not.
>From Perl perlfunc pod/man page:
shmctl ID,CMD,ARG
Calls the System V IPC function shmctl. You'll probably have to
say
use IPC::SysV;
first to get the correct constant definitions. If CMD is
`IPC_STAT', then ARG must be a variable which will hold the
returned `shmid_ds' structure. Returns like ioctl: the undefined
value for error, "`0' but true" for zero, or the actual return
value otherwise. See also `IPC::SysV' documentation.
shmget KEY,SIZE,FLAGS
Calls the System V IPC function shmget. Returns the shared
memory segment id, or the undefined value if there is an error.
See also `IPC::SysV' documentation.
shmread ID,VAR,POS,SIZE
shmwrite ID,STRING,POS,SIZE
Reads or writes the System V shared memory segment ID starting
at position POS for size SIZE by attaching to it, copying
in/out, and detaching from it. When reading, VAR must be a
variable that will hold the data read. When writing, if STRING
is too long, only SIZE bytes are used; if STRING is too short,
nulls are written to fill out SIZE bytes. Return TRUE if
successful, or FALSE if there is an error. See also `IPC::SysV'
documentation and the `IPC::Shareable' module from CPAN.
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