Replacing part of the sentence using echo and sed

Shell Programming and Scripting
1

Hi,

Iam using ksh and trying to execute the following syntax to replace one word of the sentence with a new word. But somehow sed is not able to replace the old value with new value. Please let me know where Iam going wrong.

Sample Code :

-->

export line="VORTEX,abcdef"
export isname="VORTEX"
export f_new=`echo ${line} | sed -e 's/\"${isname}\"/IDEA/g'`
echo ""$f_new

-->

Expected Result :

IDEA,abcdef

Actual Result obtained :

VORTEX,abcdef
2 
export f_new=`echo ${line} | sed -e "s/$isname/IDEA/g"`
1 Like
3

Hi Yoda,

Thanks :slight_smile: It is working.
But what I didn't get is why single quotes is not working.

Not able to understand when to use single quoates and double quotes.
Please advise.

4

Enclosing a referenced value in double quotes (" ... ") does not interfere with variable substitution.

This is called partial quoting, sometimes referred to as weak quoting.

Using single quotes (' ... ') causes the variable name to be used literally, and no substitution will take place.

This is full quoting, sometimes referred to as strong quoting.

So you have to always use double quotes or weak quoting if you want to reference a variable value.

1 Like