Examples of using grep

Tue, 16 May 2017 23:59:39 +0000

Find lines in `file1.txt` but not in `file2.txt`

grep -Fxvf file2.txt file1.txt

grep --color=auto -P '.*\([^\x00-\x7f][^\x00-\x7f][^\x00-\x7f][^\x00-\x7f][^\x00-\x7f][^\x00-\x7f]\).* file.txt

grep . oldfile > newfile

grep ^$ oldfile > newfile

or, delete really empty lines and lines with only whitespace characters

grep -E ^[[:whitespace:]]*$ oldfile > newfile

grep -rl "};" *.m | xargs sed -i .bak -e 's/};/}/'

Remarks:

grep:

sed:

If the expected changes will have string1 and string2 and the unexpected ones should not have them, use diff to find the changesets

$ diff file1.txt file2.txt > diff12.txt

and find the ones that don't have string1 and string2

    $grep -vE -e '(^.*string2|string2.*$)|^---$|^[[:digit:]]+(,[[:digit:]]+)*c[[:digit:]]+(,[[:digit:]]+)*$' diff12.txt

If you only want to count how many such lines there are, do -vEc instead of -vE.

Remarks:

-c: count but don't echo the matching lines
-v: boolean negate the test
-E: use POSIX extended regular expression
^---$|^[[:digit:]]+(,[[:digit:]]+)*c[[:digit:]]+(,[[:digit:]]+)*$ are used to match the lines "---" and "5918,5925c5918,5925" that diff generates for diff file1.txt file2.txt

Find all files:

$ find . -type f -name "*.txt" > /tmp/all.txt

Find files that contain string foobar:

$ ack -l foobar > /tmp/positive.txt

Find the complement using grep:

$ grep -v -x -f /tmp/positive.txt /tmp/all.txt

Remarks:

git help commit 10 | grep -B 1 -A 10 "\-a" | more