CODEWITHSUNDEEP
linuxbashif-statement
Ethan McTiernan
Ethan McTiernan

Reputation: 5

Bash: Why does my If-Statement always evaluate to true?

I'm trying to write what would seem to be a simple if statement in most languages, however in bash this doesnt seem to work at all.

When I run the script it always enters the first if statement. Can anyone offer help me as to what I am doing wrong?

PERC=.5
    if [  "$PERC" > "1.00" ]
            then
                    echo "Entered first statement"
            else
                    if [ "$PERC" < "1.00" ]
                            then
                                    echo "Entered second statement"
                    fi
    fi

Thanks for your help.

Upvotes: 0

Views: 340

Answers (2)

choroba
choroba

Reputation: 241758

> and < compare strings, not numbers (and must be backslashed or quoted in single [...]). Use -gt, -lt etc. to compare numbers, or use arithmetic conditions:

if (( a < b || b <= c )) ; then

Note, however, that bash only handles integer arithmetics. To compare floats, you can use bc:

if [[ 1 == $( bc <<< '1.5 < 1.00' ) ]] ; then

Upvotes: 2

Barmar
Barmar

Reputation: 780714

> and < are the I/O redirection operators. So

if [ "$PERC" > "1.0" ]

is executing the command [ "$PERC ], redirecting the output to the file 1.0, and then if is testing whether the command succeeded. [ "$PERC" ] simply tests whether "$PERC" is a non-empty string.

To use them as operators in the test command, you need to quote or escape them:

if [ "$PERC" '>' "1.0" ]

You could also use bash's [[ conditional syntax instead of the [ command:

if [[ $PERC > "1.0" ]]

Upvotes: 2

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