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


  1. How do you refer to the arguments passed to a shell script? – $1, $2 and so on. $0 is your script name.
    20. What’s the conditional statement in shell scripting? – if {condition} then … fi
    21. How do you do number comparison in shell scripts? – –eq, -ne, -lt, -le, -gt, -ge
    22. 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
    23. 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.
    24. How do you find out the number of arguments passed to the shell script? – $#
    25. What’s a way to do multilevel if-else’s in shell scripting? – if {condition} then {statement} elif {condition} {statement} fi
    26. How do you write a for loop in shell? – for {variable name} in {list} do {statement} done
    27. How do you write a while loop in shell? – while {condition} do {statement} done
    28. How does a case statement look in shell scripts? – case {variable} in {possible-value-1}) {statement};; {possible-value-2}) {statement};; esac
    29. How do you read keyboard input in shell scripts? – read {variable-name}
    30. How do you define a function in a shell script? – function-name() { #some code here return }
    31. 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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