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Compare two strings

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# 1  
Old 10-27-2010
Compare two strings
hi..
i have a problem to compare two string
my code is like that
Code:
if [[ ($1 = $username1 &&  $2 = $password1)  ||  ($1 = $username2 &&  $2 = $password2) ]]
then
echo "both data are correct"
elif [[ ($1 = $username1 &&  $2 != $password1)  ||  ($1 = $username2 &&  $2 != $password2) ]]  
echo "data is wrong"
fi

here $username1 is taking value from file..
# 2  
Old 10-27-2010
Don't recognise the syntax. What Shell are you using?
# 3  
Old 10-27-2010
I think that should be:
Code:
if [[ ($1 = $username1 &&  $2 = $password1)  ||  ($1 = $username2 &&  $2 = $password2) ]]
then
  echo "both data are correct"
else
  echo "data is wrong"
fi

IMO the elif statement is superfluous and only tests for a subset of what would be incorrect input.
# 4  
Old 10-27-2010
Assuming this is somthing like bash or ksh, it is much easier to follow with a "test" statement than a "conditional expression".


Code:
if [ "${1}" = "${username1}" -a "${2}" = "${password1}" -a "${1}" = "${username2}" -a "${2}" = "${password2}" ]
then
        echo "both data are correct"
else
        echo "data is wrong"
fi

# 5  
Old 10-27-2010
A small typo: the middle -a should be a -o.

Perhaps a matter of taste, but I for one do not agree that this is easier to follow, I think the && and || and () syntax is clearer. Also, -a and -o are deprecated. See here
# 6  
Old 10-27-2010
Quote:
A small typo: the middle -a should be a -o.
No typo. The boolean is all "and".

Strangely I've also read that the Conditional Expression [[ ... ]] is being depreciated. Depends on which set of proposed standards you read this week.
Personally I use the Conditional Expression syntax in a cron line and the "test" syntax in Shell scripts.
In the real world for this particular post I'd probably have used nested "if" statements preceded by useful comment lines.
# 7  
Old 10-27-2010
It seems to me the OP 's "both data are correct" is referring to $1 and $2. And then there should be an or in the middle IMO, no? Do you happen to have a source for your assertion that the conditional expression is being deprecated in bash/ksh?
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