Bash on OS X Lion

Code:

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flamingo:~ joliver$ cat test.sh
#!/bin/sh

case $UID in
  0 ) echo "You are running as superuser, good." ;;
  [0-9] | [0-9][0-9] | [1-4][0-9][0-9] ) echo "Should you be running as UID < 500?" ;;
  * ) echo "Regular user, proceed?"
      while [ "$ANS" != [yY] ] || [ "$ANS" != [Nn] ]
      do
        read -n 1 -s ANS
        echo $ANS
        case $ANS in
          [yY] ) echo "OK, continuing!" ;;
          [nN] ) echo "OK, exiting"; exit 0 ;;
          * ) echo "Press Y or N please" ;;
        esac
      done ;;
esac

echo "This is the end!"
flamingo:~ joliver$ bash -x ./test.sh
+ case $UID in
+ echo 'Regular user, proceed?'
Regular user, proceed?
+ '[' '' '!=' '[yY]' ']'
+ read -n 1 -s ANS
+ echo y
y
+ case $ANS in
+ echo 'OK, continuing!'
OK, continuing!
+ '[' y '!=' '[yY]' ']'
+ read -n 1 -s ANS

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Why is bash telling me 'y' is not equal to 'y'?

Greetings,

Well, from what you just posted there, it isn't telling you "'y' is not equal to 'y'"...

It's telling you that "' y '" is not equal to "'[Yy]'".

From what you posted, it looks like your read is padding $ANS with whitespace.

HTH. Let us know.

Quote:

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Originally Posted by ShadowCat8

Greetings,

Well, from what you just posted there, it isn't telling you "'y' is not equal to 'y'"...

It's telling you that "' y '" is not equal to "'[Yy]'".

From what you posted, it looks like your read is padding $ANS with whitespace.

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It does, doesn't it? Not sure why, as I did enquote the variable...

Code:

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[ "$ANS" != [yY] ] || [ "$ANS" != [Nn] ]

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Removing the spaces around the variable screws up the logic for sure. And the exact same test works in another script.

I cheated a little:

Code:

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case $UID in
  0 ) echo "You are running as superuser, good." ;;
  [0-9] | [0-9][0-9] | [1-4][0-9][0-9] ) echo "Should you be running as UID < 500?" ;;
  * ) echo "Regular user, proceed?"
      while true
      do
        read -n 1 -s ANS
        echo $ANS
        case $ANS in
          [yY] ) echo "OK, continuing!"; break ;;
          [nN] ) echo "OK, exiting"; exit 0 ;;
          * ) echo "Press Y or N please" ;;
        esac
      done ;;
esac

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