Removing text using grep

Question

Hi, i am trying to remove a line that contains a particular pattern in a text file. i have the following code which does not work

`grep -v "$varName" config.txt`

can anyone tell me how i can make it work properly, i want to make it work using grep and not sed

Answer 1

try using -Ev

grep -Ev 'item0|item1|item2|item3'

That will delete lines containing item[0-3]. let me know if this helps

Answer 2

grep doesn't modify files. The best you can do if you insist on using grep and not sed is

grep -v "$varName" config.txt > $$ && mv $$ config.txt

Note that I'm using $$ as the temporary file name because it's the pid of your bash script, and therefore probably not a file name going to be used by some other bash script. I'd encourage using $$ in temp file names in bash, especially ones that might be run multiple times simultaneously.

Answer 3

you can use sed, with in place -i

sed -i '/pattern/d' file