SC2071.md

Pattern: Use of </> in [[/[ for numerical comparison

Issue: -

Description

< and >, in both [[ and [ (when escaped) will do a lexicographical comparison, not a numerical comparison.

This means that [[ 5 > 10 ]] is true because 5 comes after 10 alphabetically. Meanwhile [[ 5 -gt 10 ]] is false because 5 does not come after 10 numerically.

If you want to compare numbers by value, use the numerical comparison operators -gt, -ge, -lt and -le.

Example of incorrect code:

if [[ $var > 10 ]]
then
  echo "Incorrectly triggers when var=5"
fi

Example of correct code:

if [[ $var -gt 10 ]]
then
  echo "Correct numerical comparison"
fi

Exceptions

If the strings happen to be version numbers and you're using <, or > to compare them as strings, and you consider this an acceptable thing to do, then you can ignore this warning.

Further Reading

• ShellCheck - SC2071