[SOLVED] Bash/awk/sed help

[Numinis]

Hi there i'm having a little problem with something i'm writing:

basicly its a forum with only one file and two commands:
./placemessage
./getmessage<nr>

the placemessage command I wrote like this:

#! /bin/bash
echo "Nickname?";
read USERNAME;
while ["$USERNAME" = ""]
do
        echo "Please enter a nickname:";
        read USERNAME;
done
echo "Subject?";
read SUBJECT;
while ["$SUBJECT" = ""]
do
        echo "Please enter a subject:";
        read SUBJECT;
done
echo "message:";
read MESSAGE;
while ["$MESSAGE" = ""]
do
do
	echo "plaats een bericht aub:";
	read MESSAGE;
done
echo nickname: $USERNAME >> myforum.txt
echo onderwerp: $SUBJECT >> myforum.txt
echo bericht: >> myforum.txt
echo  $MESSAGE >> myforum.txt
date >> myforum.txt
echo -END- >> myforum.txt
echo "" >> myforum.txt

this does work and generates the desired text in the file but when I enter text when prompted it gives me an error message on the place of the loop where I entered the text.

IE:
when entering example as username I get:
"./plaatsbericht: regel 4: [example: opdracht niet gevonden"
the same goes for subject/message.

how can I get rid of this error? I don't want to redirect the error messages tho

the second issue I have is when trying to read a message
this is the code i've been going nuts about:

this was an attempt to get the third message out of the file:

#!/bin/bash

gawk -v RS='\n\n' '{print $3}' myforum.txt

all I get is the third field and I have no idea how I get the third paragraph(record?)

so if anyone could enlighten me a bit it would be greatly appreciated, i've been messing with this for several hours now and i'm still getting nowhere

btw just giving me a code to copy/paste isn't going to help me an explanation on how it works would be more usefull to me!

thanks in advance guys!

[Cabhan]

For your first problem, the answer is that Bash is very stupid. Therefore, you actually need to leave spaces between the [ of the condition and the " of the variable:

while [ "$USERNAME" = "" ]

Also be aware that there is a better way to do this:

while [ ! -z "$USERNAME" ]

"-z" checks to see if the variable is empty.

For your second problem, $3 is the third field, not the third line, as you saw. However, the problem is also that you don't want the third line; you want the third entry as separated by -END- and a blank line.

I'm on my Mac right now, so I can't use gawk (which allows more options for the record separator, and I can check that later), but this works better than your current one anyway:

awk 'BEGIN { RS = "" }; (NR == 3) { print $0 }' myforum.txt

What this does is change the record separator to a blank line. It then prints out the third record.

What I want to test on gawk is using a regular expression for RS, particularly the regular expression "-END-\n\n", which would treat "-END-" followed by a blank line as the record separator. In the code above, the "-END-" is treated as part of the message; in this gawk regex, it will not be.

[Numinis]

entire post

I knew it had to be a stupid little error in the first one

the second one I knew I was wrong, I tried findin a way to show the third record but unfortunatly I couldn't find anything on the web nor in the book I have here.
only stuff to seperate on the field seperator

anyway in this:

awk 'BEGIN { RS = "" }; (NR == 3) { print $0 }' myforum.txt

NR is the current record which we put on 3 right? (just making sure i'm getting all of it) and the print $0 is print the entire record?

(my knowledge of awk is a bit limited, I just transfered to this class a month ago and the only language I actually master is java, thats why its all a bit overwhelming, but after all I love it, its a great way to quickly process files)

anyway thanks a lot for your help, and for the quick reply to my post

[Cabhan]

NR means number of records, and technically means the number of records encountered so far, including the current one (so yes, it is most frequently used as the current record). $1, $2, etc. are fields 1, 2, etc., but $0 is the entire record.

And awk is very complicated: whenever I use it, I need a manual to help me. But I'm glad that you're working hard on it. Good luck with your class!