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> is for string comparisons. Use -gt instead.

Problematic code:

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

Correct code:

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

Rationale:

< 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.

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.

Related resources:

• Bash Pitfalls: [[ $foo > 7 ]]
• StackOverflow: Comparing numbers in Bash

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