Examples of SED, GREP, RegEx

Cookbook of command line regex examples for sed and grep that worked for me.

1
$ sed -E s/[0-9][A-Za-z]/foooooooo/g  filename.txt

2
New line can be done by piping from sed -> tr
$ echo "123." | sed -E 's/([[:digit:]]*)\./\1|next line/' | tr '|' '\n'

3
Example with "any digit", capture group, and newline
$ echo "123z" | sed -E 's/([[:digit:]]*)z/\1\n next line/'

4
Within  a  bracket  expression, the name of a character class enclosed in "[:" and ":]" stands for the list of all characters belonging to that class.  Standard character class names are:

              alnum   digit   punct
              alpha   graph   space
              blank   lower   upper
              cntrl   print   xdigit

5
How to locate logs
sudo find / -name 'apache2' | grep log
sudo find / -name 'matomo' | grep log | sed /blog/d | sed /sql/d

How to find the fullness of the log
df -h {PATH.TO.LOG}
df -hi {PATH.TO.LOG}