Linux One Liners #linux #sed #awk #grep

links.md

Useful Links

• Unix / Linux - Regular Expressions with SED
• Regular Expressions - AWK
• 35+ Examples of Regex Patterns Using sed and awk in Linux
• Using Grep & Regular Expressions to Search for Text Patterns in Linux
• Illustrated jq tutorial
• How To Search Multiple Words / String Pattern Using grep Command on Bash shell
• The GNU Awk User’s Guide
• RegEx for Formating Rsyslog Logs to work with Arcsight Template(StackOverflow)

locale-help.txtx

Usage: locale [OPTION...] NAME
  or:  locale [OPTION...] [-a|-m]
Get locale-specific information.

 System information:
  -a, --all-locales          Write names of available locales
  -m, --charmaps             Write names of available charmaps

 Modify output format:
  -c, --category-name        Write names of selected categories
  -k, --keyword-name         Write names of selected keywords
  -v, --verbose              Print more information

  -?, --help                 Give this help list
      --usage                Give a short usage message
  -V, --version              Print program version

For bug reporting instructions, please see:
<https://bugs.launchpad.net/ubuntu/+source/glibc/+bugs>.

one-liners-awk.md

Print matched regex

(https://stackoverflow.com/questions/5536018/how-to-print-matched-regex-pattern-using-awk)
awk '/pattern/{ print $0 }' file
awk '{for(i=1;i<=NF;i++){ if($i=="yyy"){print $i} } }' file

one-liners-linux.md

Output all unique email address in a text file

cat <file.txt> | grep -oP "([a-zA-Z0-9_\-\.\*]+)@([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5})" | sort -fu

Trim leading and trailing whitespace (also mid line)

awk '{$1=$1};1'

Return header response and basic cert details from a site

curl -vvI https://gnupg.org

Return the complete certificate contents from a site

echo | openssl s_client -showcerts -servername gnupg.org -connect gnupg.org:443 2>/dev/null | openssl x509 -inform pem -noout -text

Add ZLib header to file to decompress raw

printf "\x1f\x8b\x08\x00\x00\x00\x00\x00" | cat - /tmp/data | gzip -dc >/tmp/out

For RAW Deflate add two more null bytes

"\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\x00"

Deleting the first line only (csv with headers for example)

sed '1d' file.txt > tmpfile; mv tmpfile file.txt # POSIX
sed -i '1d' file.txt # GNU sed only, creates a temporary file
perl -ip -e '$_ = undef if $. == 1' file.txt # also creates a temporary file
sed -i .bak '1d' file.txt #BSD tail -n +2 file-in.txt > file-out.txt # using Tail

regex.md

• Email addresses
  • ([a-zA-Z0-9_\-\.\*]+)@([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5})

switches.md

Grep switches

• -P, --perl-regexp
  • Interpret the pattern as a Perl-compatible regular expression (PCRE). This is experimental and grep -P may warn of unimplemented features.
• -E, --extended-regexp
  • Interpret PATTERN as an extended regular expression (ERE, see below).
• -i, --ignore-case
  • Ignore case distinctions, so that characters that differ only in case match each other.
• -o, --only-matching
  • Print only the matched (non-empty) parts of a matching line, with each such part on a separate output line.
• -c, --count
  • Suppress normal output; instead print a count of matching lines for each input file. With the -v, --invert-match option (see below), count non-matching lines.
• -v, --invert-match
  • Invert the sense of matching, to select non-matching lines.
• -a, --binary-files=text
  • Treat binary files as text (some encoding is treated as binary although it is still text)

AWK switches

Sort switches

• -f
  • Ignore Case
• -u
  • Unique

SED switches