[Solved] Linux Commands Challenge : 005

Fancy your Linux skills ? Take this challenge and answer these simple 5 questions on Linux commands.

Update : Added Solutions

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1. What does the command units do ?
• • It is a program to convert quantities expressed in one scale to another. Ex : meters to miles


2. What happens if I apply the sticky bit to a directory ?
• • You make the files in that directory “sticky”. In the sense, users cannot delete the files in that directory. Only the root user can delete the files. Ex : /tmp directory


3. How do you print the reverse of your username on Linux ?
• • whoami | rev


4. How do you find out the most commonly used command by a given user ?
• • hash | sort -r | head


5. What is the difference in the output of these two commands : echo * and ls -R ?
• • echo * : Lists all the files in the current directory and all its sub directories ls -R : Lists all the files and folders in the current directory and all its sub directories

[Solved] Linux Commands Challenge : 004

Fancy your Linux skills ? Take this challenge and answer what these 5 commonly used abbreviations of Linux stand for

Winner : Congratulations to Sankar P for getting the highest number [ 4 ] of correct solutions.

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1. What does the Linux command TAR stand for ?
• • Tape ARchive


2. What does the Linux command GREP stand for ?
• • Global ( search for ) Regular Expressions and Print


3. What does the Linux command CHMOD stand for ?
• • CHange MODe


4. What does the Linux command BC stand for ?
• • Basic Calculator


5. What does the Linux command AWK stand for ?
• • Aho, Weinberger and Kernighan. It is named after the names of its authors : Al Aho, Peter Weinberger and Brian Kernighan

[Solved] Linux Commands Challenge : 003

Fancy your Linux skills ? Take this challenge and answer these simple 5 questions on Linux Shell Scripting.

Update : Added solutions

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1. What command(s) would you use to extract the 3 words in the string “The boy laughed” ?
• • There are many variants for this. One of the solutions is as follows :
  • echo $string | cut -d” “ -f1 ; echo $string | cut -d” “ -f2 ; echo $string | cut -d” “ -f3
  • Do let me know about other possible ways to solve this through your comments to this post


2. What command(s) would you use to fetch only the 6th and 7th lines of a text file : poem.txt
• • This also has many variants. One of the solutions is as follows :
  • head -n 7 poem.txt | tail -2
  • Do let me know about other possible ways to solve this through your comments to this post


3. What command(s) would you use to delete all empty/blank lines in a file : data.txt
• • grep -v ‘^$’ data.txt


4. What does the following sed command do ? : sed -n ‘/[0-9]/p’ data.txt
• • Prints only those lines that have a numerical in them.


5. What command(s) would you use to count the number of files ending with .log in /var/log directory and also have the word “error” in their contents ?
• • grep -l error /var/log/*.log

[Solved] Linux Commands Challenge : 002

Fancy your Linux skills ? Take this challenge and answer these simple 5 questions on Linux Environment variables.

Update : Added Solutions

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1. How can variables defined in one Bash Shell script be made visible in its child Bash Shell script ?
• • You need to export the variable in the parent Bash Shell Script, for the variables to be visible in its child Bash Shell script.


2. How can one find out the type of the Shell he/she is using ?
• • echo $SHELL


3. Name the C function call that can be used in a C program to fetch the value of a Shell Environment variable
• • getenv()


4. One can use "printenv" command to list all the Global Environment variables, but what command can we use to list the Local Environment Variables ?
• • You can use "set". But, it list all the environment variables, global and local. You will have to write a Shell Script to prune out Global environment variables from the output of "set" to derive the final list of Local Environment variables. Local environment variables are the variables that are local to the current shell.


5. How can you find out the current Bash Shell's parent process id ?
• • echo $PPID