I suggest you start using real, telling variable names. You may not need it now for your example scripts but once you start writing real, working scripts you will have a hard time telling what all the i's, j's k's and what not are doing. If you search for a bird, call it "bird", not "i".
Furthermore, there is a reason why we almost religiously indent code. Consider the following code:
if <condition1> ; then
command1
if <condition2> ; then
command2
else
command3
fi
command4
fi
When is "command1" executed? Answer: if "condition1" is met. When is "command3" executed? Answer: when "condition1" is met AND "condition2" is not met. And so on - the level of indentation tells you when (or: under which conditions) a certain part of the code is executed. In your code:
for i in $birdname
do
if [[ "$REPLY" = "$i" ]]; then
echo "Yes, that is a bird."
fi
exit
if [[ ! "$REPLY" = "$i" ]]; then
echo "That is not a bird."
fi
done
When is the "exit" executed? Answer: every time. So, there is your answer why the program does not work the way you expected it. Ask yourself: under which circumstances do i want this command to be executed - and then you know where it is to be placed. We already established further up in the thread that the for-loop iterates through all the birds in your string. So ask yourself what you do want to do if the name is matched and what you want to do if not:
- get first name
- IF it matches, print "this is a bird" and exit
- IF it doesn't match, then what?
Answer: do nothing. Return to the top and get the next name. Hence:
for bird in "$all_birds" ; do
if [ "$bird" = "$REPLY" ] ; then
echo "This is a bird"
exit
fi
done
This will say "This is a bird" in case it is - but it will say nothing if it isn't. Now, if something ever matches in this loop, the "exit" command is executed and the loop is aborted. When do we ever get to the end of the loop, hm? We get there only if nothing has matched, so where is the right place to put the negative "isn't a bird" message? Yes, right:
for bird in "$all_birds" ; do
if [ "$bird" = "$REPLY" ] ; then
echo "This is a bird"
exit
fi
done
echo "This is not a bird."
Put this into your program and try it.
@joeyg: Your solution is overly complicated and not completely logically sound. First, there is a variable "NOT_FOUND", which you increment but never use. What is the purpose of an unused variable.
Second: once you find a match you carry on till the end of the birds list. This only makes sense if the same bird is mentioned more than once. i.e.
all_birds="hawk dove hawk pidgeon hawk sparrow"
REPLY="hawk"
AND you want to find out how often it is mentioned in case it is mentioned at all.
If all the birds in the list are distinct this could never happen because every possible content of "$REPLY" can be matched by either one item in the list or by none at all. Therefore you do not need a flag because you can immediately act upon the condition instead of setting a flag and act on that later. You need flags only if you need to "store" the status of a condition and act upon it later. Like, if you want to connect several conditions which you cannot evaluate at once:
flag1=0
flag2=0
if <condition1> ; then
flag1=1
fi
if <condition2> ; then
flag2=1
fi
if (( flag1 + flag2 == 2 )) ; then # only if both conditions were met (AND)
if (( flag1 + flag2 == 1 )) ; then # only if exactly one condition was met (exclusive OR)
if (( flag1 + flag2 )) ; then # if at least one condition was met (OR
if ! (( flag1 + flag2 )) ; then # if neither of the conditions were met (NOT)
Or, if you need to string different actions on the conditions or their combination:
flag1=0
flag2=0
if <condition1> ; then
flag1=1
fi
if <condition2> ; then
flag2=1
fi
if (( flag1 + flag2 )) ; then
if (( flag1 + flag2 == 2 )) ; then
actionA
fi
actionB
else
actionC
fi
if (( flag2 )) ; then
actionD
fi
I hope this helps.
bakunin