Linux Shell Programming

I had a little bit experience in Liunx Shell Progrmming through my undergraduate course work. At that time we used to create simple shell script with using only cp, grep, head, tail, mv, rm command of Shell Programming. I had never encounter with the problem of script writing for which I need to debug the script in undergraduate course. While working with some problems of shell programing in Exling LLC, I encounterd a buggy script for which I need to debug a script. At that time, I learned some features of debugging a script. I had gained a pretty well idea on debugging a script. It is much easier and essential feature of shell scripting. It solves many problems for which people may have to wait and work for many days.

I am including the buggy script first to show the  debugging features here:

#!/bin/bash
# a.sh

# This is a buggy script.
# Where, oh where is the error?

a=37

if [$a -gt 27 ]
then
  echo $a
fi 

exit 0

There are two ways to debug a script file in Shell Programing. These two ways are:
     1.  sh -v script.sh       #Display shell input lines as they are read   
     3.  sh -x script.sh       #Display commands and their arguments as they are executed

When  I used the first method I couldn't understand anything of the error in the script. Then I used the second method I can visualize the exact scenerio. Here is the output of the debugging command:

+ a=37
+ '[37' -gt 27 ']'
a.sh: line 4: [37: command not found
+ exit 0

The bug removed program is as follows:
#!/bin/bash
# a.sh

# This is a buggy script fixed.
# The Error is near the third bracket of before $a in the " if " condition. There should be a space.

a=37

if [ $a -gt 27 ]
then
  echo $a
fi 

exit 0