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Hi everyone, I'm new to Linux Shell scripting and would appreciate any help solving my issue... I'm running a script to set up Linux OS environment, the script works great but i get an error on the following portion: if [ $USERNAME != "root" ] then echo "Cannot proceed with setup.You must be logged in as root!" exit else proc=m while [ $proc != "y" -a $proc != "Y" -a $proc != "n" -a $proc != "N" ] do echo -n "Are you ready to proceed?(Y/N)" read proc if [ $proc == "n" -o $proc == "N" ] then exit else if [ $proc == "y" -o $proc == "Y" ] then continue fi fi done fi The error i get: line:2 [: !=: unary operator expected. But the script continues to run... Any help eliminating that error please! Thanks in advance.