Compare a string in Unix [duplicate]

问题:

This question already has an answer here:

• How to compare strings in Bash 10 answers
• How do I compare two string variables in an 'if' statement in Bash? [duplicate] 12 answers

I am using SH shell and I am trying to compare a string with a variable's value but the if condition is always execute to true. Why?

Here is some code:

Sourcesystem="ABC"

if [ "$Sourcesystem" -eq 'XYZ' ]; then 
    echo "Sourcesystem Matched" 
else
    echo "Sourcesystem is NOT Matched $Sourcesystem"  
fi;

echo Sourcesystem Value is  $Sourcesystem ;

Even this is not working:

Sourcesystem="ABC"

if [ 'XYZ' -eq "$Sourcesystem" ]; then 
    echo "Sourcesystem Matched" 
else
    echo "Sourcesystem is NOT Matched $Sourcesystem"  
fi;

echo Sourcesystem Value is  $Sourcesystem ;

Secondly, can we match this with a NULL or empty string?

回答1:

You should use the = operator for string comparison:

Sourcesystem="ABC"

if [ "$Sourcesystem" = "XYZ" ]; then 
    echo "Sourcesystem Matched" 
else
    echo "Sourcesystem is NOT Matched $Sourcesystem"  
fi;

man test says that you use -z to match for empty strings.

回答2:

-eq is used to compare integers. Use = instead.

回答3:

I had this same problem, do this

if [ 'xyz' = 'abc' ];
then
echo "match"
fi

Notice the whitespace. It is important that you use a whitespace in this case after and before the = sign.

Check out "Other Comparison Operators".

回答4:

eq is used to compare integers use equal '=' instead , example:

if [ 'AAA' = 'ABC' ];
then 
    echo "the same" 
else 
    echo "not the same"
fi

good luck

回答5:

-eq is the shell comparison operator for comparing integers. For comparing strings you need to use =.

回答6:

-eq is a mathematical comparison operator. I've never used it for string comparison, relying on == and != for compares.

if [ 'XYZ' == 'ABC' ]; then   # Double equal to will work in Linux but not on HPUX boxes it should be if [ 'XYZ' = 'ABC' ] which will work on both
  echo "Match"
else
  echo "No Match"
fi

回答7:

Of the 4 shells that I've tested, ABC -eq XYZ evaluates to true in the test builtin for zsh and ksh. The expression evaluates to false under /usr/bin/test and the builtins for dash and bash. In ksh and zsh, the strings are converted to numerical values and are equal since they are both 0. IMO, the behavior of the builtins for ksh and zsh is incorrect, but the spec for test is ambiguous on this.