Babak K. Shandiz
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Living in the Shell #3; grep (Pattern Matching) (Part 2)

Living in the Shell #3; grep (Pattern Matching) (Part 2)

Babak K. Shandiz's photo
Babak K. Shandiz
·Nov 26, 2021·

1 min read

grep🎖️

Prints/filters lines that match a Regular Expression (RE) pattern.

Print line numbers -n

echo -n 'Hello World!\nI''m Going!\nGoodbye!' | grep -n "G."
  2:Im Going!
  3:Goodbye!

Print lines around (after/before) every match -A -B

cat ~/.bashrc | grep "if" -A 5 -B 1

Prints next 5 lines and previous 1 line when caught any "if".

Only check silently (no output) -q

cat ~/.bashrc | grep -q "alias"

Returns with 0 exit code on any match, otherwise 1.

Count matching lines -c

cat ~/.bashrc | grep -c "alias"

Print only matching substring -o

echo -n 'Hello World!\nI''m Going!\nGoodbye!' | grep -o "G..d"
  Good
 
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