Bash conditions always evaluate true in script

Question

I have a condition which seems to always be evaluated as true.

#!/bin/bash

checkFolder() {
    echo "[checkFolder]"
    echo "check $1"
    [ -n "$1" ] && [ -d "$1" ] && return 0
    echo "[/checkFolder]"
    return 1
}

rootFolder=$1

echo "check $rootFolder"
checkFolder "$rootFolder"
echo "res: $res"   # !! <--- I omitted this test line, as I thought it was irrelevant. 
echo "ret: $?"

When I execute my script, any path will give me a return value of 0. Which means that any string I provide seems to be seen as non-empty as well as an existing directory. I tried with:

./myScript.sh "."
./myScript.sh ""
./myScript.sh "wqert"

I will aways get a return value of 0. How comes? If I run this command in my terminal:

param=""
[ -n "$param" ] && [ -d "$param" ] && echo ok
# returns nothing

param="hello"
[ -n "$param" ] && [ -d "$param" ] && echo ok
# returns nothing

param="/home"
[ -n "$param" ] && [ -d "$param" ] && echo ok
# returns "ok"

Why doesn't it work in my script?

Do you believe that setting a variable named param will result in $1 taking on that value? — that other guy
– that other guy, Commented Oct 28, 2015 at 22:58
For the command in the termianl, that was a mistake, I just corrected it. However, in my script function checkFolder, $1 does take the argument passed as a value. So my problem remains. — kaligne
– kaligne, Commented Oct 28, 2015 at 23:02
@kaligne So, now you have your answer: that echo line is relevant. It sets an exit code and the final echo "ret: $?" returns the exit code of the preceding echo statement. — John1024
– John1024, Commented Oct 28, 2015 at 23:13
Thanks for the hint, I realised the problem came from a line I omitted, as I thought it was irrelevant here. I added it in my post: echo "res: $res", which comes before my call to $?. So now I guess an echo returns the value 0 here? Is there an other way for me to retrieve the return value aside from the variable $? ? — kaligne
– kaligne, Commented Oct 28, 2015 at 23:13

that other guy · Accepted Answer · 2015-10-28 23:13:37Z

4

$? is the exit code of the last executed command. In your case, the last executed command is echo, not checkFolder.

If you want to execute other commands between running a command and checking its status, assign it to a variable with myvar=$?

answered Oct 28, 2015 at 23:13

that other guy

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user2350426 · Accepted Answer · 2015-10-29 00:15:20Z

1

What the command return changes is the "exit code" of the function.
Add this:

 checkFolder "$rootFolder"
 echo "the exit code was $?"

And see the effect of your return 0 and return 1.

answered Oct 29, 2015 at 0:15

user2350426

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