shell script

xlord · 10-31-2002, 05:47 PM

For some reason i cant get this code to work perfectly can anyone help..
its bash programming

Code:

echo "please enter second passwd";
pass="******************"
read pass

if ["$pass" == "pass"]; 
 then
  echo "passwd correct you may procced"
else 
  if ["pass" -eq "$pass"]; then 
  echo "pass incorrect"
 fi   
fi

acid_kewpie · 10-31-2002, 06:18 PM

well it's a bit of a mess really. -eq is an integer comparison, and you are using strings, so that won't work. and if it did work then it would be the same as the first if statement. you have a bizarre half nested if block.. by the else statement you already know it is not matching, yet you check it again? and of course you will get a syntax error as there is no space between [ and ] and the quotes. [ is a program, not just a bracket. i'd strongly suggesting buying a bash book and taking a bit more time.

acid_kewpie · 10-31-2002, 06:20 PM

hmm, that read a bit harsh ehh? sorry!

also though... you don't need all those semi-colons, that's just to continue on the same line, not like c / java. and you don't need to put quotes around your echo statements. I also get the impression that you're going to hardcode a password into a plain text bash file? i *seriously* hope this is just to learn bash....

xlord · 10-31-2002, 06:23 PM

No that is ok harsh is good sometimes.. but im a newbie at shell scripting.. i really dont have money to get a book yet.. but if you can help me fix this... or if you can fix my code.. with were i have the errors.. then i can understand more.. if ok with you

acid_kewpie · 10-31-2002, 06:31 PM

it's normally against my religion to solve peoples code for them, but...

Code:

echo please enter second passwd
read pass

if [ $pass == pass ]
 then
  echo passwd correct you may procced
  # DO SOMETHING
else 
  echo pass incorrect
  # DO SOMETHING ELSE
fi

xlord · 10-31-2002, 06:36 PM

Hhmm that is weard ... as far as i know.. from the tuts that i have read.. i see
if [ "blah" =="blah" ] but since i removed them and added another space in [] now it works.. but why... when i read a tut in some site...(will find site again) it says that it is the correct way?

btw thanx for your help!

acid_kewpie · 10-31-2002, 06:41 PM

run " ls -l `which [` " you wouldn't expect something like

Code:

 if testblah == blah

to work now would you?

unSpawn · 10-31-2002, 08:36 PM

Uhm, not to intrude here, but may I warn agains unquoted variables since the shell usually separates everything thrown at it by space?: if [ "$pass" = "pass" ]; then
And you won't need a double equal sign.

xlord · 10-31-2002, 09:05 PM

well its fine this way.. just one more prob.. it keeps saying pass is not correct.. for some reason.. errr its really anoying check it out

Code:

echo "please enter second passwd"
pass="***********"
read pass

if [ $pass == pass ]
 then
  echo "passwd correct you may procced"

elif [ $pass != pass ]
 then
  echo "pass incorrect"

else
  echo "Please enter pass"

fi

i cant see to understand why

unSpawn · 10-31-2002, 09:17 PM

execute as "sh -x <scriptname>"

xlord · 10-31-2002, 09:21 PM

ok i did that and this is what i got..

Code:

[xlordt@local xlordt]$ sh -x test
+ echo 'please enter second passwd'
please enter second passwd
+ pass=*********
+ read pass

+ '[' pass == ']'
test: [: pass: unary operator expected
+ '[' pass '!=' ']'
test: [: pass: unary operator expected
+ echo 'Please enter pass'
Please enter pass

Mik · 11-01-2002, 05:07 AM

There is no difference between the last two if branches. $pass is either equal to pass or not, it can't also be something different. If you wanted to check for an empty $pass then you should do something like:

if [ -z "$pass" ]
then
echo "Please enter pass"
fi

unSpawn · 11-01-2002, 07:53 AM

If you had listened to my advice and properly quoted variables you would have ended up with "if [ "$pass" = "pass" ]" , which in turn would translate in bashspeak to
'if' '[' '' '=' 'pass' ']'. By not quoting and then providing an empty value for pass you end up with one part where "=" (thats binary operator) cannot operate on.

Like Mik suggested you should test for empty string.
I like to do it like this:

if [ "${pass:?"not_defined"}" = "pass" ]; then echo "passwd correct you may procced"; else echo "Please enter pass"; fi
This way it always gets assigned a (bogoid) value indicating zomesing's vrronkk.

If you haven't got money to buy a book, at least use the ABS: http://www.tldp.org/LDP/abs/html/

xlord · 11-01-2002, 01:33 PM

ahh yes sorry i was abit waisted last night.. but thanx i finaly got it working all =)

dogmeat · 11-01-2002, 01:49 PM

wasted on what