i mean can a different script replace cron job and run a nother script each our .
or can i add a timer to a script so it eclute each hour
with out taking all system memorie
while (1) {
# do your stuff here
sleep 3600;
}
But this would have disadvantages compared to cron - eg if the script failed in some way, it would stop it executing all the subsequent times the hour rolled around rather than just failing in that one instance. You'd also have to be very careful to clear variables etc at the end of each loop or you'd end up experiencing memory problems and/or unexpected results.
Is cron not available to you on your host?
- Have your main script generate a static file with it's output when it runs. (ie. the headlines of a news source)
- Load a script with each call of the page that is supposed to show the main script, and check the age of the static file generated by your main script. If it's less then an hour old use that, otherwise run the main script again before you use the static file.
the sleep loop i like to avoid as it has memorie risks
if i make sloppy code as i do as beginner.
server can easy crash on memorie run out ...
yeh run script based on as soon it gets requested could be done then i can use sleep without a loop
when site is called run script then sleep 3500
then next visitors activates it again
how can one script start a nother script?
In that case you don't need one script to trigger another, but you would need to change the behaviour of your mainscript to give output based on the static file.
'sleep' would not be needed at all in this scenario.
>how can one script start another script?
You can write something like this in the script that should trigger myscript.cgi:
require "home/cgi-bin/myscript.cgi";
script 1 checks how old (minutes) a time.txt file is .
if older then 1 hour then run sub next
how can a script check how old a file.txt is?
thats all new to me ,i thit not even know that where posible ;-)
yeh no need for sleep and no memorie drops this way ....
[perl]
# Update interval in seconds
$interval = 1800;
# current time
$now = time;
#if the file exists, get it's properties
if ( -f file.txt) {
($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks) = stat(file.txt);
$difference = $now - $mtime;
}
# trigger the "Update" sub routine (not included in this example) to create a new copy of file.txt
if ( $difference > $interval ¦!-f file.txt) {&Update(file.txt);
[/perl]
This board changes the pipe characters, so change the split pipes back to regular pipes in the code above
$lastUpdate = (stat($file))[9];
#if the file exists, get it's propertiesif ( -f file.txt) {
$lastUpdate = (stat(file.txt))[9];
$difference = $now - $lastUpdate;
}
- this adds nothing new, it's just another way. What i wanted to say was, that i would prefer this order to things:
1) check time
2) deliver page
3) if time is due, then run update.
That is: Not in the order 1,3,2 as suggested above.
This way the person that hits the page at the time of update will get the latest page delivered without having to wait for the update to finish. Then, a later visitor will get the updated page, but it will be delivered faster.
/claus
$lastUpdate = (stat($file))[9];
Very slick Claus, I've not come across that construction before... I've always used the same method as Damian and never thought to do it that way. Thanks.
# Update interval in seconds
$interval = 1800;
# current time
$now = time;
#if the file exists, get it's properties
if ( -f time.txt) {
$lastUpdate = (stat(time.txt))[9];
$difference = $now - $lastUpdate;
}
# trigger the "Update" sub routine (not included in this example) to create a new copy of time.txt
if ( $difference > $interval?!-f time.txt) {&Update(time.txt);
sub Update {
open(FILE, "> time.txt") or die " Cant open time.txt: $!";
print FILE "";
close(FILE);
}
Thank all this looks good ..
i made sub Update . it reads time.txt delete all lines
its not making new file justclear all is in, but this gives also new time to the file right?
as last time used is now time that sub Update clean it?
if i try this the script would only run sub Update if the file is older then $interval = 1800;
am i right?
I just remembered the other way to get a file's age is
$days_old = -M file.txt;
It returns the number of days file.txt is old. (with a lot of number behind the comma) So if $days_old would be > 0.0416 the file is older then an hour approximatly.
Stopspam, there's a bracket missing at the end of this line (my mistake)
{&Update(time.txt);
it should be {&Update(time.txt);}
>if i try this the script would only run sub Update if the file is older then $interval = 1800;
> am i right?
Right, just write the output of your script to file.txt where you clear it now, and serve the content of file.txt to your visitors instead of 'live' output from the script.
SN
14 # trigger the "Update" sub routine (not included in this example) to create a new copy of time.txt
15 if ( $difference > $interval?!-f time.txt) {&Update(time.txt);}
Line 15 syntax error at /home/web/www/cgi-bin/robot/timeclean.cgi line 15, near "txt) "
- there's a space after $interval
- then a pipe (you can not copy this one : ¦ it needs to be typed from the keyboard so it will not be split. You have a questionmark here.
- then the rest.
Hope it helps.
/claus
Debugging goes ok i get a nice script OK!
but when i try to run the script i get a Internal Server Error ....
i think its the part to get the time: $now = time;
should i add time to the script like;
$date = scalar localtime ( time ); ?
here is code i used but fails ...
i had chmod the time.txt file 666
#########
#!/usr/local/bin/perl
$interval = 1800;
# current time
$now = time;
if ( -f time.txt) {
$lastUpdate = (stat(time.txt))[9];
$difference = $now - $lastUpdate;
}
if ( $difference > $interval ¦!-f time.txt) {&Update(time.txt);
print " time past $difference\n";
sub Update {
open(FILE, "> time.txt") or die " Cant open time.txt: $!";
print FILE "";
close(FILE);
print " time past $difference has pasted file is cleaned\n";
}
}
There's an error in your script above with the placement of brackets.
- Remove the last closing bracket, and add it to the line below
Also please try to put the time.txt between quotes, I think that's what caused your error initially before you went debugging ;) Sorry..
- change this line
if ( $difference > $interval ¦!-f time.txt) {&Update(time.txt);
to
if ( $difference > $interval ¦! -f "time.txt") {&Update;}
I removed the reference to time.txt in &Update(time.txt) because it serves no purpose in your Update sub routine.
i use this code:
and all it do is grap print $now that works
it aint print $lastUpdate or $difference its
like the script ends here or server dont know what to return?
i added all print lines so ican see if each functionworks .. it only prints $now
#!/usr/local/bin/perl
print "Content-type: text/html\n\n";
$interval = 1800;
$now = time;
print " print now: $now\n\n";
print "\n\n";
if ( -f time.txt) {
$lastUpdate = (stat(time.txt))[9];
$difference = $now - $lastUpdate;
}
if ( $difference > $interval ¦! -f "time.txt") {&Update;}
print " print last update: $lastUpdate \n";
print " show difference: $difference\n";
sub Update {
open(FILE, "> time.txt") or die " Cant open time.txt: $!";
print FILE "";
close(FILE);
print " diff is; $difference file time.txt has been cleaned!\n";
}
#######
i also found this using google:
#!/usr/bin/perl
$now = time;
utime $now, $now, @ARGV;
whats the utime $now, $now,?
should i use it?
[perl]
#!D:\perl\bin\perl.exe
use CGI::Carp qw(carpout fatalsToBrowser);
print "Content-type: text/html\n\n";
$interval = 2;
# current time
$now = time;
if ( -f "time.txt") {
$lastUpdate = (stat("time.txt"))[9];
$difference = $now - $lastUpdate;
}
if ( $difference > $interval ¦!(-f "time.txt")) {&Update; }
print " time past $difference\n";
sub Update {
open(FILE, "> time.txt") or die " Cant open time.txt: $!";
print FILE "";
close(FILE);
print " time past $difference has passed file is cleaned\n";
}
[/perl]
In the final version, we still have:
if ( -f "time.txt") {
and then later, this:
if ( $difference > $interval ¦ !(-f "time.txt")) {&Update; }
I just wanted to note that this construct requires two checks to see if the file exists - usually an inefficient process, since it involves the file system. It would be better/faster to check once, set a var, and then use that var for all subsequent checks. Or just restructure the code so that a second check for the existence of time.txt is not needed.
That said, thanks to all for the collaborative code snippet, several good tricks there... Copied into my "library" already. :)
Jim
can you show me a sample of the code you mention in:
It would be better/faster to check once, set a var, and then use that var for all subsequent checks.
faster is better script i think ...
In case there are more files, which may not exist yet, I think this is what Jim has in mind more or less. My example uses the variable $file_exists, which is set to 1 if the file exists. I changed the occurences of 'time.txt' into a the variable $file because that's a more realistic situation when dealing with multiple files that need to be checked, and it changes the syntax slightly with the usage of quotes.
I also made some changes to the printed text to make a little more sense :)
[perl]
#!E:\perl\bin\perl.exe
use CGI::Carp qw(carpout fatalsToBrowser);
print "Content-type: text/html\n\n";
#interval time in seconds
$interval = 2;
# current time
$now = time;
# the static file
$file = "time.txt";
my $file_exists = 0;
if ( -f $file) {
$file_exists = 1;
$lastUpdate = (stat($file))[9];
$difference = $now - $lastUpdate;
}
if ( $difference > $interval ¦ $file_exists == 0) {&Update; }
print "Time passed $difference\n";
sub Update {
open(FILE, "> $file") or die " Cant open $file: $!";
print FILE "";
close(FILE);
print "$file was updated<br>\n";
}
[/perl]
