Bashscripts.org

HI
I am a newbie at script writting:

I am in the process of learning scripting using bash:
The book i use is UNIX SHELLS BY EXAMPLE by Ellie Quigley

I have to write a script that will check for new mail and write a
message to my screen; This is how the question is written:

The program will get the size of the mail spool file for the user.
The script will execute in a contunuous loop,once every 30 seconds. Each time the loop executes, it will compare the size of the mail spool file with its size from the previous loop. If the new size is greater than the old size, a message will be printed on my screen, saying (Username, You have mail).

From what i know so far bash as already a mail program.
All i have to do is type mail and it tell me if i got mail.
If i understand this correctly this is not email from the web or freinds:
Its mail from lets say if i was connected to a network, is this correct:
This one got me stump:
Maybe it because it to easy i gest:
I am using suse 10.0
Got your web site from suse cool solutions page:


Well thanks in advance:

hmmm well, lets help you get started

program will get the size of the mail spool file for the user.
perhaps something like

once every 30 seconds.


a message will be printed on my screen, saying (Username, You have mail).



See if that helps get you started

Well this is what i have so far;
the formula give me a loop every 30 second and give me the
right info ($user, You have mail) but;
on the second pass if i send myself a new mail it dosen't evaluate the old wc -l count with the new wc -l count:
As you can see i have to loop every 30 second and if i recived
some new mail it as to tell me (I have new mail):
I tried every way i could figure out but nothing works;
The book that i am using to learn all of this dosen't give me
the answer and it limited on the example; So i have to use site
like this (and the help of guys like you) to see if i am wright with what i do
{ This is the script i came up with so far}

while [ $USER = (name) ]
do
wc -l /var/spool/mail/$USER
sleep 30
old=`wc -l /var/spool/mail/$USER`
new=`wc -l /var/spool/mail/$USER`
if [ "$old" = "$new" ]
then
echo "$USER, You have mail"
elif [ "$old" != "$new" ]
then
echo "$USER, You have new mail"
fi
done

one thing you can do... is check to see where the script is bombing.
like directly after assigning the variables, "old" and "new", see what they were assigned with.


I think you will see that old and new have stuff other than numbers

YMMV

Now, is it telling you the same message everytime? The "You have mail" or is it saying "You have new mail" everytime?

one thing I would change too... just for testing... is the elif statement.

instead of:

just use

and see which message you get everytime.
and post

[/code][/quote]
one thing you can do... is check to see where the script is bombing.
like directly after assigning the variables, "old" and "new", see what they were assigned with.


I think you will see that old and new have stuff other than numbers

YMMV

Now, is it telling you the same message everytime? The "You have mail" or is it saying "You have new mail" everytime?

one thing I would change too... just for testing... is the elif statement.

instead of:

just use

and see which message you get everytime.
and post [/quote]

Well did what you guys said:
I rewrote the script this way'

while [ $USER = (name) ]
do
old=`wc -l /var/spool/mail/$USER`
new=`wc -l /var/spool/mail/$USER`
if [ "$old" = "$old" ]
then
echo "$old"
echo "$USER, You have mail"
else [ "$new" != "$old" ]
echo "$new"
echo "$USER, You have new mail"
fi
done
It stays at the ("$USER, You have mail")
it never pass that line even if i send myself new mail.
it as if it dosent evalluate the new (wc -l) of the new message.
It echo ($old) all the time:never the ($new). The only thing that
works is the loop;
From what i can see, is it add the new count to the old:
It never pass the first (if) dosent go to the (else) for the new count::cry:
I am not good enough to debug this scripts yet: I just can't figure it out;

ok... let me explain what is going on...
you have a script running a loop...
inside that loop you are assigning the variable old... and the variable new
you are then asking if old is the same as old...
ofcourse it is
you just told it to be...
so... try this...
OUTSIDE the loop... right before the while... put the old=`blah`
then... inside the loop... assign new just like you have it...
then... the if statement shouldn't read if [ "$old" = "$old" ]
it should read if [ "$new" = "$old" ]

then... right after the part that says "you have NEW mail"
add the line... old="$new"

and you should have yourself a nice working script

A big thanks for the help I sure need it:
I finally got the script working in the wright direction:
Like i said the book i am using to learn scripting does'nt
give answer so i don't know if i am wright or wrong, or if its working properly:
in the wright direction:
Again Thanks

you're very welcome...
post what you have so we can see how you fixed it...

i'm interested to see which angle you took...
i feel scripting is like an artform... there are different ways to put paint on the canvas... how do you do it?

o ya... and welcome to Bashscripts.org... if you havn't already... check out usalug.org, and if you use suse... opensuse.us
they are all offiliated

Sorry for the delay was away for a few days.
Here is the script i wrote for the mail loop.

old=""
do
while [ "USER" = (name) ]
new=`/var/spool/mail/USER`
if [ "new" = "old" ]
echo "USER, You have mail"
else [ "new" != "old" ]
echo "USER< You have new mail"
fi
sleep 30
done
It does what it supposed to do acording to the question in
the book i am using.
Well I hope i did it okay this time it.
Once again THANKS.

hey there pappy... gladd you got it sorted out...

i'm thinking i would have done something like...

the concept of what you wrote makes sense.. but it is NOT syntaxically (yes i just made up that word ) correct.
in other words... exactly how you have it above... would error if ran.

in my version, it would run... statically for one user. I would probably make the user more dynamic, and allow the person who runs it to choose what user account to monitor,,, and ofcourse with that comes better error checking and the whole nine...

I just want to hear jbsnake actually pronounce syntaxically

Again sorry for the delay in reply
Okay i will use your advise on the script for like i said i am new
to all of this:
And yes crouse i think i would like to see anyone try to pronouce that word;