how to start the tomcat server in linux?

if you are a sudo user i mean if you got sudo access:

      sudo sh startup.sh 

otherwise: sh startup.sh

But things is that you have to be on the bin directory of your server like

cd /home/nanofaroque/servers/apache-tomcat-7.0.47/bin

Use ./catalina.sh start to start Tomcat. Do ./catalina.sh to get the usage.

I am using apache-tomcat-6.0.36.

The command you have typed is /startup.sh, if you have to start a shell script you have to fire the command as shown below:

$ cd /home/mpatil/softwares/apache-tomcat-7.0.47/bin
$ sh startup.sh 
or 
$ ./startup.sh 

Please try that, you also have to go to your tomcat's bin-folder (by using the cd-command) to execute this shell script. In your case this is /home/mpatil/softwares/apache-tomcat-7.0.47/bin.