>Usage
awk (Text Processing and Pattern Scanning Language) is a powerful language used for text processing and pattern scanning. It’s like a Swiss Army knife for text manipulation – you can use it to search, filter, and modify data, often in columns or structured data, making it ideal for analyzing files like logs or CSVs.
>Synopsis
>Options
-F
-F (field separator): Defines the field separator for splitting the text into columns.
Example 1:
-zsh
> echo "apple orange banana" | awk -F" " '{print $1}'
apple
$
$ (field reference): Refers to individual fields in the input (e.g., $1, $2).
Example 2:
-zsh
> echo "apple orange banana" | awk '{print $2}'
orange
NR
NR (Number of Records): Refers to the number of lines processed.
In the example below, NR specifies that only the second line should be processed, and the action prints the first field ($1) of the selected line, where fields are separated by whitespace by default.
Example 3:
-zsh
> echo -e "apple\norange\nbanana" | awk 'NR == 2 {print $1}'
orange
BEGIN
BEGIN: Executes a set of instructions before processing any input. This is useful for initializing special variables.
Example 4:
-zsh
> echo -e "apple\norange\nbanana" | awk 'BEGIN {print "Start processing"} {print $1}'
Start processing
apple
orange
banana
END
END: Executes commands after all input is processed.
Example 5:
-zsh
> echo -e "apple\norange\nbanana" | awk 'END {print "Finished processing"}'
Finished processing
pattern-action
pattern-action: Defines an action to take when a pattern is matched.
Example 6:
-zsh
> echo -e "apple\norange\nbanana" | awk '/orange/{print "Found orange"}'
Found orange
print (default action): Prints the entire line or specified fields.
Example 7:
-zsh
> echo "apple orange banana" | awk '{print $1, $3}'
apple banana
if-else
if-else: Conditional processing based on patterns or data.
Example 8:
-zsh
> echo "apple orange" | awk '{if ($1 == "apple") print "It is apple"}'
It is apple