I have a script that will find the distances between two atoms in pdb.
bash does not recognize decimals so I have put printf script to round the decimals.
and echo $b works fine and gives me a integer value.
but the if line for my filtering system does not work.
I get and error stating
[: -ge: unary operator expected
below is part of the script that I am working on.
a=$(awk '$2=='91'{x1=$6;y1=$7;z1=$8} $2=='180' {x2=$6;y2=$7;z2=$8} END{print sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2) + (z1-z2)*(z1-z2))}' ${names}.pdb.$i)
b= printf %.0f $a
echo $b
if [ $b -ge 1 ] &&[ $b -le 9 ]; then
any help will be greatly appreciated. Thank you in advanced.
b= printf %.0f $a
This line sets the value of b to nothing for the duration of the printf command, which sends its output to stdout
echo $b
This prints a blank line.
You must not put whitespace around the = in an assignment, and to store the output of a command into a variable, you use this syntax:
b=$( printf %.0f $a )
You're getting the error because $b is empty, and this is what bash sees:
if [ -ge 1 ] &&[ -le 9 ]; then
-ge is expecting operands on both the left and the right, and it doesn't see one.
With bash, you should (almost) always prefer [[ ... ]] over [ ... ] -- the double bracket form is not fooled by variables containing empty strings.
You should always quote your "$variables" -- unless you know exactly when to not quote them.