Linux/Basic commands/awk

AWK is a language/utility designed and used mainly for text processing.

Basic 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 line if field value is larger than:

awk '$FIELD_NUMER>VALUE'

Example: awk '$4>3.1416'

Activities

1. Read stackoverflow awk questions: https://stackoverflow.com/questions/tagged/awk?tab=Votes

See also

• sed
• tr to replace or remove specific characters from input data
• grep and ag