Difference between the output of echo ** and echo * *
echo ** lists all the filenames in the current directory..
echo * * lists all the filenames in the current directory twice.
 

The other way of running shell script apart from using sh command and chmod?
ans:- using ! we can run a shell script
 

How do you refer to the arguments passed to a shell script? 
$1, $2 and so on. $0 is your script name.
 

What’s the conditional statement in shell scripting? 
if {condition} then … fi
 

How do you do number comparison in shell scripts? 
-eq, -ne, -lt, -le, -gt, -ge
 

How do you test for file properties in shell scripts? 
-s filename tells you if the file is not empty, -f filename tells you whether the argument is a file, and not a directory, -d filename tests if the argument is a directory, and not a file, -w filename tests for writeability, -r filename tests for readability, -x filename tests for executability
 

How do you do Boolean logic operators in shell scripting? 
! tests for logical not, -a tests for logical and, and -o tests for logical or.
 

How do you find out the number of arguments passed to the shell script? 
$#
 

What’s a way to do multilevel if-else’s in shell scripting?
if {condition} then {statement} elif {condition} {statement} fi
 

How do you write a for loop in shell?
for {variable name} in {list} do {statement} done
 

How do you write a while loop in shell? 
while {condition} do {statement} done
 

How does a case statement look in shell scripts? 
case {variable} in {possible-value-1}) {statement};; {possible-value-2}) {statement};; esac
 

How do you read keyboard input in shell scripts? 
read {variable-name}
 

How do you define a function in a shell script? 
function-name() { #some code here return }
 

How does getopts command work? 
The parameters to your script can be passed as -n 15 -x 20. Inside the script, you can iterate through the getopts array as while getopts n:x option, and the variable $option contains the value of the entered option.

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