cgi using shell script : unexpected behavior

15/03/2008, 01h26

Hi everyone,
I'm writing a small shell script to act like a cgi
program. I have linked this script to a basic site I have developed
via a form. I have attached the code below, and would greatly
appreciate any pointers to correct glaring mistakes

..

The problem: Everything displays as expected until I hit the second if
statement. When I uncomment this statement all I get is a blank page,
If I comment out this part ( if [ $flag1 -e 1 ]; then ) then I see
what should be displayed until this point. The syntax for the if
statement seems correct... I can't figure out what stupid mistake is
causing this error

To recap: When I comment out the part if [ $flag1 -e 1 ]; then, I can
see Your URL is www.hfdjhgjghjgh.com and then the flag1 value. As soon
as I enable the if part I see a blank page! arrrrgh! please :-)

#!/bin/sh

wd=$PWD

echo "Content-type: text/html"
echo

echo "<HTML><HEAD><TITLE>My first cgi</Title></HEAD>"
echo " <BODY>"
echo " <pre>"

input=(`echo "$QUERY_STRING"`)

#check for ; and |
flag=(`echo $input | awk 'BEGIN{flag=0} /;|%3B/{flag=1} /\||%7C/
{flag=2} END{print flag}'`)

if [ $flag -e 0 ];
then
echo "Malformed URL: invalid characters used"
echo "Please check URL"
else
burl=(`echo $input | awk '{split($0,a,"&");split(a[1],b,"=")

rint
b[2]}'`);
echo "<H3>Your URL is </H3> $burl";
#push this in psql db and check if we know
#about it
echo "SELECT sitename FROM urltable WHERE sitename = '$burl';" >
$wd/query.sql
flag1=(`psql -f $wd/query.sql urldb | awk 'BEGIN{a=0} /(0 rows)/
{a=1} END{print a}'`)
echo $flag1

if [ $flag1 -e 1 ]; then
#PROBLEM IS HERE
else
#do something
fi
#return the formatted page
fi
rm -f $wd/query.sql
echo "</BODY>"
echo "</HTML>"
exit

15/03/2008, 02h35

On Mar 14, 5:26 pm, newbiegalore <banerjee.anir...@gmail.com> wrote:
> Hi everyone,
> I'm writing a small shell script to act like a cgi
> program. I have linked this script to a basic site I have developed
> via a form. I have attached the code below, and would greatly
> appreciate any pointers to correct glaring mistakes

..
>
> The problem: Everything displays as expected until I hit the second if
> statement. When I uncomment this statement all I get is a blank page,
> If I comment out this part ( if [ $flag1 -e 1 ]; then ) then I see
> what should be displayed until this point. The syntax for the if
> statement seems correct... I can't figure out what stupid mistake is
> causing this error
>
> To recap: When I comment out the part if [ $flag1 -e 1 ]; then, I can
> see Your URL iswww.hfdjhgjghjgh.comand then the flag1 value. As soon
> as I enable the if part I see a blank page! arrrrgh! please :-)
>
> #!/bin/sh
>
> wd=$PWD
>
> echo "Content-type: text/html"
> echo
>
> echo "<HTML><HEAD><TITLE>My first cgi</Title></HEAD>"
> echo " <BODY>"
> echo " <pre>"
>
> input=(`echo "$QUERY_STRING"`)
>
> #check for ; and |
> flag=(`echo $input | awk 'BEGIN{flag=0} /;|%3B/{flag=1} /\||%7C/
> {flag=2} END{print flag}'`)
>
> if [ $flag -e 0 ];
> then
> echo "Malformed URL: invalid characters used"
> echo "Please check URL"
> else
> burl=(`echo $input | awk '{split($0,a,"&");split(a[1],b,"=")

rint
> b[2]}'`);
> echo "<H3>Your URL is </H3> $burl";
> #push this in psql db and check if we know
> #about it
> echo "SELECT sitename FROM urltable WHERE sitename = '$burl';" >
> $wd/query.sql
> flag1=(`psql -f $wd/query.sql urldb | awk 'BEGIN{a=0} /(0 rows)/
> {a=1} END{print a}'`)
> echo $flag1
>
> if [ $flag1 -e 1 ]; then
> #PROBLEM IS HERE
> else
> #do something
> fi
> #return the formatted page
> fi
> rm -f $wd/query.sql
> echo "</BODY>"
> echo "</HTML>"
> exit

OK things seem to be working!! don't really know why though

.. I
removed all the text/blank spaces near the ifs and then re-wrote the
code there.. got my fingers crossed.

-A

15/03/2008, 03h51

On 2008-03-15, newbiegalore <banerjee.anirban@gmail.com> wrote:
>
>
> #check for ; and |
> flag=(`echo $input | awk 'BEGIN{flag=0} /;|%3B/{flag=1} /\||%7C/
> {flag=2} END{print flag}'`)
>
> if [ $flag -e 0 ];

I think you men if [ $flag -eq 0 ];
Actually it should be if [ "$flag" -eq 0 ]; Shell variables should be
quoted unless you want them to undergo word splitting and filename
expansion.

15/03/2008, 04h51

On Mar 14, 7:51 pm, Bill Marcum <marcumb...@bellsouth.net> wrote:
> On 2008-03-15, newbiegalore <banerjee.anir...@gmail.com> wrote:
>
>
>
> > #check for ; and |
> > flag=(`echo $input | awk 'BEGIN{flag=0} /;|%3B/{flag=1} /\||%7C/
> > {flag=2} END{print flag}'`)
>
> > if [ $flag -e 0 ];
>
> I think you men if [ $flag -eq 0 ];
> Actually it should be if [ "$flag" -eq 0 ]; Shell variables should be
> quoted unless you want them to undergo word splitting and filename
> expansion.

Hey thanks man! :-)

15/03/2008, 05h40

My test:
socket micro_inetd:
http://www.acme.com/software/

In a xterm:
$ micro_inetd 8888 /tmp/cgi

In the browser:
http://localhost:8888/

Some changes in your script:
$ cat /tmp/cgi
#!/bin/sh

wd=$PWD

#echo "Content-type: text/html"
#echo

echo -en "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n"

echo "<HTML><HEAD><TITLE>My first cgi</Title></HEAD>"
echo " <BODY>"
echo " <pre>"

set -x # for debug only

input=(`echo "$QUERY_STRING"`)

#check for ; and |
flag=(`echo $input | awk 'BEGIN{flag=0} /;|%3B/{flag=1} /\||%7C/
{flag=2} END{print flag}'`)

if [ $flag -eq 0 ];
then
echo "Malformed URL: invalid characters used"
echo "Please check URL"
else
burl=(`echo $input | awk '{split($0,a,"&");
split(a[1],b,"=")

rint b[2]}'`);
echo "<H3>Your URL is </H3> $burl";
#push this in psql db and check if we know
#about it
echo "SELECT sitename FROM urltable WHERE sitename = '$burl';" >
$wd/query.$
flag1=(`psql -f $wd/query.sql urldb | awk 'BEGIN{a=0} /(0 rows)/
{a=1} END{$
echo $flag1

if [ $flag1 -eq 1 ]; then
echo PROBLEM IS HERE
else
echo do something
fi
#return the formatted page
fi
rm -f $wd/query.sql
echo "</BODY>"
echo "</HTML>"
exit

Another example, to play:
Basic HTTPD CGI script
###############
$ cat /tmp/http
#!/bin/bash
printf "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n\r\n"
echo ---------BROWSER:
while [ "$REPLY" != $'\r' ];do read -r -t1;[ "$P" ]||P=$REPLY;echo
"$REPLY";done
echo ---------SERVER noHEADER:
echo \$0=$0;echo P=$P
P=${P#*/};echo P=$P
P=${P% *};echo P=$P
P=${P//%20/ };echo P=$P
date;ls -l /bin/*sh|grep -- ^-
echo ---------END
$ micro_inetd 8888 /tmp/http
$ lynx "http://localhost:8888/here, my parms"

15/03/2008, 01h26	#1
newbiegalore Messages: n/a Hébergeur:	cgi using shell script : unexpected behavior Hi everyone, I'm writing a small shell script to act like a cgi program. I have linked this script to a basic site I have developed via a form. I have attached the code below, and would greatly appreciate any pointers to correct glaring mistakes .. The problem: Everything displays as expected until I hit the second if statement. When I uncomment this statement all I get is a blank page, If I comment out this part ( if [ $flag1 -e 1 ]; then ) then I see what should be displayed until this point. The syntax for the if statement seems correct... I can't figure out what stupid mistake is causing this error To recap: When I comment out the part if [ $flag1 -e 1 ]; then, I can see Your URL is www.hfdjhgjghjgh.com and then the flag1 value. As soon as I enable the if part I see a blank page! arrrrgh! please :-) #!/bin/sh wd=$PWD echo "Content-type: text/html" echo echo "<HTML><HEAD><TITLE>My first cgi</Title></HEAD>" echo " <BODY>" echo " <pre>" input=(`echo "$QUERY_STRING"`) #check for ; and \| flag=(`echo $input \| awk 'BEGIN{flag=0} /;\|%3B/{flag=1} /\\|\|%7C/ {flag=2} END{print flag}'`) if [ $flag -e 0 ]; then echo "Malformed URL: invalid characters used" echo "Please check URL" else burl=(`echo $input \| awk '{split($0,a,"&");split(a[1],b,"=")rint b[2]}'`); echo "<H3>Your URL is </H3> $burl"; #push this in psql db and check if we know #about it echo "SELECT sitename FROM urltable WHERE sitename = '$burl';" > $wd/query.sql flag1=(`psql -f $wd/query.sql urldb \| awk 'BEGIN{a=0} /(0 rows)/ {a=1} END{print a}'`) echo $flag1 if [ $flag1 -e 1 ]; then #PROBLEM IS HERE else #do something fi #return the formatted page fi rm -f $wd/query.sql echo "</BODY>" echo "</HTML>" exit

15/03/2008, 02h35	#2
newbiegalore Messages: n/a Hébergeur:	Re: cgi using shell script : unexpected behavior On Mar 14, 5:26 pm, newbiegalore <banerjee.anir...@gmail.com> wrote: > Hi everyone, > I'm writing a small shell script to act like a cgi > program. I have linked this script to a basic site I have developed > via a form. I have attached the code below, and would greatly > appreciate any pointers to correct glaring mistakes .. > > The problem: Everything displays as expected until I hit the second if > statement. When I uncomment this statement all I get is a blank page, > If I comment out this part ( if [ $flag1 -e 1 ]; then ) then I see > what should be displayed until this point. The syntax for the if > statement seems correct... I can't figure out what stupid mistake is > causing this error > > To recap: When I comment out the part if [ $flag1 -e 1 ]; then, I can > see Your URL iswww.hfdjhgjghjgh.comand then the flag1 value. As soon > as I enable the if part I see a blank page! arrrrgh! please :-) > > #!/bin/sh > > wd=$PWD > > echo "Content-type: text/html" > echo > > echo "<HTML><HEAD><TITLE>My first cgi</Title></HEAD>" > echo " <BODY>" > echo " <pre>" > > input=(`echo "$QUERY_STRING"`) > > #check for ; and \| > flag=(`echo $input \| awk 'BEGIN{flag=0} /;\|%3B/{flag=1} /\\|\|%7C/ > {flag=2} END{print flag}'`) > > if [ $flag -e 0 ]; > then > echo "Malformed URL: invalid characters used" > echo "Please check URL" > else > burl=(`echo $input \| awk '{split($0,a,"&");split(a[1],b,"=")rint > b[2]}'`); > echo "<H3>Your URL is </H3> $burl"; > #push this in psql db and check if we know > #about it > echo "SELECT sitename FROM urltable WHERE sitename = '$burl';" > > $wd/query.sql > flag1=(`psql -f $wd/query.sql urldb \| awk 'BEGIN{a=0} /(0 rows)/ > {a=1} END{print a}'`) > echo $flag1 > > if [ $flag1 -e 1 ]; then > #PROBLEM IS HERE > else > #do something > fi > #return the formatted page > fi > rm -f $wd/query.sql > echo "</BODY>" > echo "</HTML>" > exit OK things seem to be working!! don't really know why though .. I removed all the text/blank spaces near the ifs and then re-wrote the code there.. got my fingers crossed. -A

15/03/2008, 03h51	#3
Bill Marcum Messages: n/a Hébergeur:	Re: cgi using shell script : unexpected behavior On 2008-03-15, newbiegalore <banerjee.anirban@gmail.com> wrote: > > > #check for ; and \| > flag=(`echo $input \| awk 'BEGIN{flag=0} /;\|%3B/{flag=1} /\\|\|%7C/ > {flag=2} END{print flag}'`) > > if [ $flag -e 0 ]; I think you men if [ $flag -eq 0 ]; Actually it should be if [ "$flag" -eq 0 ]; Shell variables should be quoted unless you want them to undergo word splitting and filename expansion.

15/03/2008, 04h51	#4
newbiegalore Messages: n/a Hébergeur:	Re: cgi using shell script : unexpected behavior On Mar 14, 7:51 pm, Bill Marcum <marcumb...@bellsouth.net> wrote: > On 2008-03-15, newbiegalore <banerjee.anir...@gmail.com> wrote: > > > > > #check for ; and \| > > flag=(`echo $input \| awk 'BEGIN{flag=0} /;\|%3B/{flag=1} /\\|\|%7C/ > > {flag=2} END{print flag}'`) > > > if [ $flag -e 0 ]; > > I think you men if [ $flag -eq 0 ]; > Actually it should be if [ "$flag" -eq 0 ]; Shell variables should be > quoted unless you want them to undergo word splitting and filename > expansion. Hey thanks man! :-)

15/03/2008, 05h40	#5
mop2 Messages: n/a Hébergeur:	Re: cgi using shell script : unexpected behavior My test: socket micro_inetd: http://www.acme.com/software/ In a xterm: $ micro_inetd 8888 /tmp/cgi In the browser: http://localhost:8888/ Some changes in your script: $ cat /tmp/cgi #!/bin/sh wd=$PWD #echo "Content-type: text/html" #echo echo -en "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n" echo "<HTML><HEAD><TITLE>My first cgi</Title></HEAD>" echo " <BODY>" echo " <pre>" set -x # for debug only input=(`echo "$QUERY_STRING"`) #check for ; and \| flag=(`echo $input \| awk 'BEGIN{flag=0} /;\|%3B/{flag=1} /\\|\|%7C/ {flag=2} END{print flag}'`) if [ $flag -eq 0 ]; then echo "Malformed URL: invalid characters used" echo "Please check URL" else burl=(`echo $input \| awk '{split($0,a,"&"); split(a[1],b,"=")rint b[2]}'`); echo "<H3>Your URL is </H3> $burl"; #push this in psql db and check if we know #about it echo "SELECT sitename FROM urltable WHERE sitename = '$burl';" > $wd/query.$ flag1=(`psql -f $wd/query.sql urldb \| awk 'BEGIN{a=0} /(0 rows)/ {a=1} END{$ echo $flag1 if [ $flag1 -eq 1 ]; then echo PROBLEM IS HERE else echo do something fi #return the formatted page fi rm -f $wd/query.sql echo "</BODY>" echo "</HTML>" exit Another example, to play: Basic HTTPD CGI script ############### $ cat /tmp/http #!/bin/bash printf "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n\r\n" echo ---------BROWSER: while [ "$REPLY" != $'\r' ];do read -r -t1;[ "$P" ]\|\|P=$REPLY;echo "$REPLY";done echo ---------SERVER noHEADER: echo \$0=$0;echo P=$P P=${P#/};echo P=$P P=${P% };echo P=$P P=${P//%20/ };echo P=$P date;ls -l /bin/*sh\|grep -- ^- echo ---------END $ micro_inetd 8888 /tmp/http $ lynx "http://localhost:8888/here, my parms"

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