Copy value of 1 variable into another variable in UNIX

Question

New to Unix not aware of the syntax structure so please excuse my syntax brevity.I am trying to copy a value of a variable and store that in another variable eg:

Two variables:

abc
bcd

Given:

abc=123

I want to copy the contents of abc i.e 123 in bcd. How to achieve this in Unix?

Earlier I was trying to copy the contents of abc in a .txt file which was working for me: see the code snippet below:

abc='123'
echo $abc >>/data/test/tt.txt

But know I want to copy them in another variable so I tried to do the following but was of no success.

    abc='123'
    test=`echo $abc>>bcd`
    echo $test

Can you assist me in this?

Hey @vidit that works, i have a scenario where the value of abc will be incremented eg: abc="123" then abc="456" i want bcd to have both the values — Rahul sawant
– Rahul sawant, Commented Dec 8, 2013 at 23:46
you expect a variable to have two values? Maybe you should look into Quantum Mechanics. — vidit
– vidit, Commented Dec 8, 2013 at 23:50

rodrigo · Accepted Answer · 2013-12-08 23:49:16Z

3

Easy:

bcd="$abc"

For example:

abc="hello world"

The quotes there are necessary or else it will try to run a command named world with abc in its environment.

Actually, the quotes are not necessary (thanks to 1_CR for pointing this), but I like to add them for readability:

bcd=$abc
bcd="$abc"

They both do the same, exactly what you need.

Lastly, do not use single quotes, or else you will not get the value of the variable:

bcd='$abc'

Error! Now your bcd variable contains the literal value $abc.

edited Dec 8, 2013 at 23:49

answered Dec 8, 2013 at 23:30

rodrigo

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8 Comments

iruvar Over a year ago

Quotes not needed in ksh variable assignment apparently

Rahul sawant Over a year ago

Yes the above works, but what in a scenario where the value of abc will be incremented eg abc="123" then abc="456" now here i want bcd to have both the values which are bcd="123 456" how can we achieve this?

rodrigo Over a year ago

@1_CR: You are right! They are not needed in bash either! You always learn something in SO, even in the apparently easiest questions.

rodrigo Over a year ago

To increment the variable you'll do abc="$abc 456". And here the quotes are necessary. Or if you don't want the space: abc=${abc}456, then you don't need the quotes.

Rahul sawant Over a year ago

I can do that when i know the what the next incremented value of abc will be like in this case abc="$abc 456" what if we do not knw what the next value will be

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