Tracing a shell script!!!

Hi all,

I would like to know how to trace a shell script..

I meant i used the set -x command and also tried,
$ bash -xv <script name>
but the problem is am a newbie and did not understand what those + and ++ meant at the beginning of each line...(once the execution of the script starts), there were lots of stuff that i couldnt understand....

Also i would like to know if there is a provision like F7 in C/C++ to trace the calls made, line by line...

Thanks

Traditionally, a SysAdmin captures Log The Standard Output (1) & The Standard Error (2) of commands of a script to a file

for example
#execute_command 2>&1 log.file