Awk

wikipedia:AWK

Examples

• Prepend a variable string ($STRING_TO_PREPEND) at the beginning of every line

cat file.txt | awk '{print "'$STRING_TO_PREPEND' "$0}'

In case text to prepend is a variable ($PREPEND_TEXT_VAR):

echo "$ORIGINAL_TEXT" | awk -v AWK_PREPEND_VAR="$PREPEND_TEXT_VAR" '{print AWK_PREPEND_VAR" "$0}'

Prepend time before every line

echo "$ORIGINAL_TEXT" | awk -v time="$(date)" '{print time" "$0}'

• Remove leading spaces at the beginning of a line:

awk ' {$1=$1} 1 '

• Print lines if field fith value ($5) is smaller than 100:

awk '$FIELD_NUMER>VALUE'

Example: awk '$5<100'

See also

• ack, ag, grep, egrep, fgrep, agrep, ngrep, pgrep, awk, sed, strings, tr, tail, mtail, git grep, wc, uniq, LogQL, findstr (Windows), rg, git-grep, cut
• Editors: vi, vim, sed, awk, emacs, lineinfile (Ansible), Atom, paste, Neovim, Rider, visudo, vipw, update-alternatives, nano, more, less, .vimrc, set (vi) zed

https://serverfault.com/questions/72744/command-to-prepend-string-to-each-line

https://catonmat.net/awk-one-liners-explained-part-two