README.md

Process textfiles in an awk-like manner, but with python syntax.

Example:

$ echo x y z | prawk -t 'print(F[-2])' -
y

Supported variables:

• BEGIN (True on first record in first file)
• END (True on last record in last file)
• FNR (current record number in current file, restarts at 1 for each file)
• NR (current record number, total running number)
• F (the fields of current record)
• NF (number of fields of current record)

Keywords:

• NEXT is used to skip to next line (matches next in awk)

Differences from awk

BEGIN and END

BEGIN and END statements are performe when processing the first and last record respectively. They to NOT occur before or after processing records. This is to avoid surprises and technical difficulties of running the prawk script with a record loaded. Therefore, you might want to specify BEGIN clauses in the beginning of your program and END clauses at the end of your program.

Fruit examples

These examples operate on examples/fruit_prices.txt with this content:

Banana 150
Apple 10
Citrus 200
Blueberries 30
Strawberries 30

• Add a running line number to each line:

$ prawk -t 'print(NR, F[0])' examples/fruit_prices.txt
1 Banana 150
2 Apple 10
3 Citrus 200
4 Blueberries 30
5 Strawberries 30

• Calculate the sum of a specific column: With a program file like this:

$ cat examples/total_sum.py
if BEGIN: s=0
s+=F[2]
if END: print(f"Total: {s}")

Supply the above script to prawk:

$ prawk -f examples/total_sum.py examples/fruit_prices.txt
Total: 420

Multiple files example

Using a second input file:

David Banana 1
David Strawberries 5
Monica Citrus 3

And combine it using this script:

if BEGIN:
    costs = {}
    total = {}
if FNR == NR:
    costs[F[1]] = F[2]
    NEXT

if F[1] not in total: total[F[1]] = 0
total[F[1]] += costs[F[2]] * F[3]

if END: print(f"Total: {total}")

To calculate the total cost per person:

$ prawk -f examples/total_order_cost.py examples/fruit_prices.txt examples/fruit_orders.txt
Total: {'David': 300, 'Monica': 600}