[SOLVED] How to select (grep) many different patterns by bash via a pipe?

Issue

My task
I have a file A.txt with the following content.

aijdish uhuih
buh iiu hhuih
zhuh hiu
d uhiuhg ui
...

I want to select lines with these words aijdish, d, buh ... I only know that I can:

cat A.txt | grep "aijdish" > temp.txt
cat A.txt | grep "d" >> temp.txt
cat A.txt | grep "buh" >> temp.txt
...

But I have several thousands of words need to select this time, how can I do this under bash?

Solution

Since you have many words you want to look for I suggest putting the pattern into a file and use greps -f option:

$ cat grep-pattern.txt
aijdish
buh
d

$ grep -f grep-pattern.txt inputfile
aijdish uhuih
buh iiu hhuih
d uhiuhg ui

But if you have words like d you might want to add the -w option to match only whole words and not parts of words.

grep -wf grep-pattern.txt inputfile

Answered By - ahilsend

Answer Checked By - Marie Seifert (WPSolving Admin)