How to find and remove multiple sub strings in a string

Question

I have an input as follows

Input File Name : a.txt

-- Some Comment

delete from tb.Test WHERE id = 'abxd1';

delete from tb1.Test WHERE id = 'abxd2';

-- Some Comment

delete from tb1.Table1 WHERE id = 'abxd3';

Expected output file : b.txt

-- Some Comment

delete from Test WHERE id = 'abxd1';

delete from Test WHERE id = 'abxd2';

-- Some Comment

delete from Table1 WHERE id = 'abxd2';

The following code will just replace the value "tb.". I am trying to make this as a generic script.

while read line
do
   str=$line
   echo "${str/tb./}" >>b.txt
done <$1

Thanks for you help

hek2mgl · Accepted Answer · 2014-06-25 15:16:35Z

1

You could use sed:

sed 's/delete from \(tb[0-9]\?\).\([[:alnum:]]\+\)/delete from \2/g' input.file

answered Jun 25, 2014 at 15:16

hek2mgl

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3 Comments

hek2mgl Over a year ago

What do you mean with sub string?

Ullan Over a year ago

what I meant to say is the some string that need to be removed, basically anything after "from" till "." In the above example "tb.", "tb1.". sorry for not asking the question completely.

hek2mgl Over a year ago

I don't get, I could just guess. You need to explain more.

Harsh Gupta · Accepted Answer · 2014-06-25 15:28:21Z

0

You can do it using sed:

echo $str | sed -r 's/tb[a-z0-9_]*.//g'

HTH

answered Jun 25, 2014 at 15:28

Harsh Gupta

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Comments

marcello · Accepted Answer · 2014-06-25 21:45:28Z

0

Assuming that you want to remove X. in delete from X.Y (everything before the DOT and the DOT), it is even simpler:

sed 's/delete from .*\./delete from /' a.txt

and you can use the -i option to overwrite the same file

sed -i 's/delete from .*\./delete from /' a.txt

HTH, Marcello

edited Jun 25, 2014 at 21:45

answered Jun 25, 2014 at 15:33

marcello

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2 Comments

Ullan Over a year ago

what if I want to remove anything after "delete from" to .(DOT including tb. tb1. or abc.), so the output will be delete from test ..

marcello Over a year ago

in that case: sed 's/delete from .*\./delete from /' a.txt (I've updated the answer above accordingly)

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