Bash Hybrid

This guide demonstrates how to combine the power of awk with Bash to process delimited text files. We’ll compare a pure awk script to a Bash/awk hybrid, then progressively build a reusable salary‐benchmarking tool.

Why Bash-AWK Hybrids?

Pure awk scripts are concise for text processing.
Embedding awk inside Bash adds flexibility (variables, flags, CLI args).
Shebangs (#!/usr/bin/env …) let you run scripts directly.

Pure awk Script (`salary.awk`)

#!/usr/bin/env awk -f
BEGIN {
    FS = "|"
}
{
    print $2, $3
}

Bash Script Embedding awk (`print_names.sh`)

#!/usr/bin/env bash
awk -F "|" '{
    print $2, $3
}'

You can run either script by:

chmod +x print_names.sh
./print_names.sh < employees.txt

Or invoke awk directly:

awk -f salary.awk employees.txt

Preparing the Data Source

Our employees.txt file uses | as the field separator and contains:

Column No	Field	Description
1	Employee ID	Unique identifier
2	First name	Given name
3	Last name	Family name
4	Department	Department name
5	Job title	Position title
6	Email	Contact email
7	Salary	Annual salary (USD)

The image shows a text file named "employees.txt" containing a list of employees with details such as name, department, job title, email, and salary.

Set the field separator with -F or FS to split on |.

Salary Thresholds

Threshold Variable	Criteria
`high_salary`	Salary ≥ 90000 (high earners)
`low_salary`	Salary ≤ 65000 (potential bumps)

1. Basic One-Liner

Print first name, last name, and salary for every employee:

awk -F "|" '{ print $2, $3, $7 }' employees.txt

Output:

Kriti Shreshtha 60000
Rajasekar Vasudevan 75000
Debbie Miller 80000
Enrique Rivera 65000
Feng Lin 90000
Andy Luscomb 95000
Mark Crocker 85000
Jing Ma 100000

2. Filter by Salary Range

Use -v to pass thresholds into awk:

awk -F "|" \
    -v high_salary=90000 \
    -v low_salary=65000 \
    '$7 >= high_salary || $7 <= low_salary {
        print $2, $3, $7
    }' employees.txt

This shows both high and low earners in one stream.

3. Add a Header with `BEGIN`

Introduce a one-time header via BEGIN:

awk -F "|" \
    -v high_salary=90000 \
    -v low_salary=65000 \
    -v header="==== Salary Adjustments ====" \
    'BEGIN { print header }
     $7 >= high_salary || $7 <= low_salary {
         print $2, $3, $7
     }' employees.txt

4. Wrap into a Bash Script (`salary.sh`)

For readability and reuse, move the awk call into a Bash script:

#!/usr/bin/env bash

awk -F "|" \
  -v high_salary=90000 \
  -v low_salary=65000 \
  -v header="==== Salary Adjustments ====" '
BEGIN {
  print header
}
$7 >= high_salary || $7 <= low_salary {
  print $2, $3, $7
}
' < employees.txt

Make it executable and run:

chmod +x salary.sh
./salary.sh

5. Separate “Up” and “Down” Sections (`salary-v2.sh`)

Print distinct headers for high and low salaries:

#!/usr/bin/env bash

awk -F "|" \
  -v high_salary=90000 \
  -v low_salary=65000 \
  -v up_header="===== Needs to be adjusted up =====" \
  -v down_header="===== Needs to be adjusted down =====" '
$7 >= high_salary {
  print down_header
  print $2, $3, $7
}
$7 <= low_salary {
  print up_header
  print $2, $3, $7
}
' < employees.txt

6. One Header per Group (`salary-v3.sh`)

Use flags inside awk to avoid repeating headers:

#!/usr/bin/env bash

awk -F "|" \
  -v high_salary=90000 \
  -v low_salary=65000 \
  -v up_header="===== Needs to be adjusted up =====" \
  -v down_header="===== Needs to be adjusted down =====" '
$7 <= low_salary {
  if (!printed_up_header) {
    print up_header
    printed_up_header = 1
  }
  print $2, $3, $7
}
$7 >= high_salary {
  if (!printed_down_header) {
    print down_header
    printed_down_header = 1
  }
  print $2, $3, $7
}
' < employees.txt

7. Parameterize with CLI Arguments (`salary-v4.sh`)

Allow users to override thresholds when running the script:

#!/usr/bin/env bash

readonly UP_HEADER="===== Needs to be adjusted up ====="
readonly DOWN_HEADER="===== Needs to be adjusted down ====="

high_salary="${1:-90000}"
low_salary="${2:-65000}"

awk -F "|" \
  -v high_salary="$high_salary" \
  -v low_salary="$low_salary" \
  -v up_header="$UP_HEADER" \
  -v down_header="$DOWN_HEADER" '
$7 >= high_salary {
  if (!printed_down_header) {
    print down_header
    printed_down_header = 1
  }
  print $2, $3, $7
}
$7 <= low_salary {
  if (!printed_up_header) {
    print up_header
    printed_up_header = 1
  }
  print $2, $3, $7
}
' < employees.txt

Run with defaults:

chmod +x salary-v4.sh
./salary-v4.sh

Or specify custom thresholds:

./salary-v4.sh 80000 60000

Next Steps

You’ve now explored:

Pure awk vs Bash/awk hybrids
Using -v to pass variables into awk
Conditional headers with BEGIN and internal flags
Parameterizing scripts via CLI

Practice customizing these scripts for different file formats, field counts, or more complex filtering logic.

Introduction

Conventions

Refresher

Streams

Expansions - Part One

Globs

Expansions - Part Two

Special Shell Variables

Arrays

Good Practices applied

awk

sed

Why Bash-AWK Hybrids?

Pure awk Script (`salary.awk`)

Bash Script Embedding awk (`print_names.sh`)

Preparing the Data Source

Salary Thresholds

1. Basic One-Liner

2. Filter by Salary Range

3. Add a Header with `BEGIN`

4. Wrap into a Bash Script (`salary.sh`)

5. Separate “Up” and “Down” Sections (`salary-v2.sh`)

6. One Header per Group (`salary-v3.sh`)

7. Parameterize with CLI Arguments (`salary-v4.sh`)

Next Steps

References

Watch Video

Practice Lab

​Why Bash-AWK Hybrids?

​Pure awk Script (salary.awk)

​Bash Script Embedding awk (print_names.sh)

​Preparing the Data Source

​Salary Thresholds

​1. Basic One-Liner

​2. Filter by Salary Range

​3. Add a Header with BEGIN

​4. Wrap into a Bash Script (salary.sh)

​5. Separate “Up” and “Down” Sections (salary-v2.sh)

​6. One Header per Group (salary-v3.sh)

​7. Parameterize with CLI Arguments (salary-v4.sh)

​Next Steps

​References

Watch Video

Practice Lab

Why Bash-AWK Hybrids?

Pure awk Script (`salary.awk`)

Bash Script Embedding awk (`print_names.sh`)

Preparing the Data Source

Salary Thresholds

1. Basic One-Liner

2. Filter by Salary Range

3. Add a Header with `BEGIN`

4. Wrap into a Bash Script (`salary.sh`)

5. Separate “Up” and “Down” Sections (`salary-v2.sh`)

6. One Header per Group (`salary-v3.sh`)

7. Parameterize with CLI Arguments (`salary-v4.sh`)

Next Steps

References