grep examples

# Color highlithing with grep
tail -f /var/log/mail | grep --color -E '<regex>|$'

# Print unvisible symbols
LC_ALL="C" grep '^.*[^[:print:]]\+' имя_файла

# Multiple grep with xargs
grep from.*linux.domain.tld /var/log/mail|awk '{print $6}'|xargs -I{} grep {} /var/log/mail|grep "client="|awk '{print $7}'|sort|uniq -c

# Extract all IP from log
cat log.smbd*bz2|bunzip2|egrep -o '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'|sort -u

watch "smbstatus 2>/dev/null |egrep -o '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'|sort -u >tmp.log && cat smb-ip.log >> tmp.log && cat tmp.log|sort -u > smb-ip.log && cat smb-ip.log|wc -l && cat smb-ip.log"

# Search \t
grep --perl-regex "CNAME\t${domain}"

# Print N strings after found:
grep -A<N> "found" file
# Print N strings before found:
grep -B<N> "found" file

# Extract emails from file:
grep -oe "[a-zA-Z0-9._]\+@[a-zA-Z]\+.[a-zA-Z]\+" emails.txt