Alle Zeilen mit # Am Anfang ergaenzen.

:%s@^@#&@

find -maxdepth 1 -type d -not -name "*hide*"

= Show all directories directly located in the current directory which do not have the word 'hide' in their name.

Useful and fast:

find -type f -name 'filename' -exec grep -H 'text to find' {} +

Same result and maybe even better performance:

Put all pdf's you want to combine in a directory. Name them in the order, you want to combine them.

qpdf --empty --pages *.pdf -- NameOfMergedFile.pdf

Easy way to repeat often used commands on the linux console ... add history search backwards to .inputrc in your home directory:

cd ~

vim .inputrc

cd /into/directory/one_level_above

grep -rnw . -e 'string to be searched'
 

With image styles and responsive breakpoints drupal generates automatically smaller images from the original uploaded ones.

cd dir_containing_files

sed -i '/_core\:/d' *
sed -i '/default_config_hash/d' *

Get all lines in a big file containing some text:

cat filename  | egrep "141.71.45.20|159.205.92.236|171.33.185.210|"

Thanks to Günter!

dig domainname.tld

To really see all DNS entries for the domain, add option ANY:

dig domainname.tld ANY