[SOLVED] Help with bash for loop

woodson2 · 10-19-2020, 02:45 PM

The code below works just fine as long as the exit status equals 0, however I'd like the script to exit after 3 times if the exit status is non-zero. Right now the script continues on even if the exit status is non-zero after the 3 iterations.

Code:

for run in {1..3}
do
kinit $USER
   if [ $? -eq 0 ]; then
   echo ""
    echo -e "${bldgrn}Good. Now lets us continue${txtrst}"
     echo ""
      sleep .5
       break
   else
    sleep 1
    echo -e "${bldred}Please verify your credentials and try again!${txtrst}"
   fi
done

teckk · 10-19-2020, 04:24 PM

Code:

if [ $? -eq 0 ]

That will always be 0

Code:

echo $USER
me
echo $?
0

echo $UUSERRRR
echo $?
0

Are you testing for kinit or $USER

Code:

a="fred"
b=""

if [ -z "$a" ]; then
    echo "a is empty"
else
    echo "a is "$a""
fi
a is fred

if [ -z "$b" ]; then
    echo "b is empty"
else
    echo "b is "$b""
fi
b is empty

[[ ! -z "$a" ]] && echo "Not empty" || echo "Empty"
Not empty
[[ ! -z "$b" ]] && echo "Not empty" || echo "Empty"
Empty

astrogeek · 10-19-2020, 04:28 PM

You do not have any test to exit after three times around the loop, instead you have a loop which runs three times - not the same thing.

Instead of setting the loop to run three times, I would write an endless loop which breaks on the success condition (exit status zero), and exits after three unsuccessful trips around the loop. To do that we need a loop counter and two tests.

Here is one way to do it:

Code:

loop_count=0
while [ 1 -gt 0 ] ; do
    ((loop_count++))
    echo "Verifying..."
    kinit $USER
    #Break loop on success
    if [ $? -eq 0 ]; then
        break;
    fi
    #Exit with error after third fail
    if [ $loop_count -ge 3 ]; then
        exit 1;
    fi
    echo "Please try again..."
    sleep 1;
done

#Arrive here only on success within three tries
echo "Continuing..."

woodson2 · 10-19-2020, 04:36 PM

Quote:

Originally Posted by astrogeek

You do not have any test to exit after three times around the loop, instead you have a loop which runs three times - not the same thing.

Instead of setting the loop to run three times, I would write an endless loop which breaks on the success condition (exit status zero), and exits after three unsuccessful trips around the loop. To do that we need a loop counter and two tests.

Here is one way to do it:

Code:

loop_count=0
while [ 1 -gt 0 ] ; do
    ((loop_count++))
    echo "Verifying..."
    kinit $USER
    #Break loop on success
    if [ $? -eq 0 ]; then
        break;
    fi
    #Exit with error after third fail
    if [ $loop_count -ge 3 ]; then
        exit 1;
    fi
    sleep 1;
done

#Arrive here only on success within three tries
echo "Continuing..."

This is precisely what I needed. Thank you.

astrogeek · 10-19-2020, 05:05 PM

You are welcome, glad it helped!

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