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Practice Scripts — Zero to Hero Shell Scripting

A numbered, beginner-friendly progression through shell scripting. Follow the scripts in order from 01 to 18 — each one builds on the previous.

Run any script with:

bash 01_hello.sh
# or make it executable first
chmod +x 01_hello.sh && ./01_hello.sh

The sequence

Phase 1 — Output, variables, input

# Script What you'll learn
01 01_hello.sh Shebang #!/bin/bash, echo, comments
02 02_variables.sh Variable assignment, expansion, $(command) substitution
03 03_arguments.sh Script args: $0, $1, $#, $@
04 04_user_input.sh Interactive input with read -p

Phase 2 — File operations & operators

# Script What you'll learn
05 05_create_file.sh touch, chaining with && and ||
06 06_install_package.sh Parameterized sudo apt-get install

Phase 3 — Conditionals

# Script What you'll learn
07 07_if_else.sh if [[ ]] … else … fi, string comparison ==
08 08_if_file_exists.sh File test -f, arg count $#, exit 1
09 09_if_elif_else.sh Multi-branch with numeric -ge and string checks

Phase 4 — Loops

# Script What you'll learn
10 10_for_loop_list.sh for x in list and glob patterns
11 11_for_loop_counter.sh C-style for (( )) to create N folders
12 12_while_loop.sh while [[ ]] with arithmetic $((...))

Phase 5 — Functions

# Script What you'll learn
13 13_functions.sh Define and call a function
14 14_function_with_args.sh Functions with parameters ($1 inside function)
15 15_source_and_call.sh source another script and reuse its functions

Phase 6 — Real DevOps tasks

# Script What you'll learn
16 16_create_user.sh Full workflow: input → check with id → useradd
17 17_system_details.sh Pipes + awk for memory, disk, and process info
18 18_error_handling.sh set -e, exit codes, if ! func; then exit 1

Phase 7 — Capstone: backups + cron

# Script What you'll learn
19 19_backup.sh tar -czf gzip archive, timestamped filenames, retention cleanup

19_backup.sh applies everything from 01–18: variables, $(date), functions, if-checks, set -e, conditionals. It creates a timestamped .tar.gz of practice-scripts/ and keeps only the last 7 backups.

Run manually:

bash 19_backup.sh
# backups go to ~/shell-backups/ by default
# override with: BACKUP_DIR=/my/path bash 19_backup.sh

Schedule with cron (periodic backups):

Open your crontab:

crontab -e

Add one of these lines (replace the path with your actual repo path):

# every day at 2 AM
0 2 * * * /bin/bash /Users/shubhamlondhe/Documents/work/TrainWithShubham/courses/udaan-batch-11/Shell-Scripting-For-DevOps/practice-scripts/19_backup.sh >> /tmp/backup.log 2>&1

# every hour
0 * * * * /bin/bash /path/to/practice-scripts/19_backup.sh >> /tmp/backup.log 2>&1

# every 15 minutes (testing only)
*/15 * * * * /bin/bash /path/to/practice-scripts/19_backup.sh >> /tmp/backup.log 2>&1

Cron field order: minute hour day-of-month month day-of-week command. Use crontab.guru to build/test expressions.

List your scheduled jobs: crontab -l. Remove all: crontab -r.

What's next? (Cloud)

You've finished zero-to-hero basics. For real-world cloud automation, study these advanced scripts in the parent repo (they apply everything above plus AWS CLI and Docker):

  • ../day03/deploy_django_app.sh — multi-step Docker deployment from a Git repo
  • ../day03/create_ec2.sh — provision an AWS EC2 instance end-to-end with set -euo pipefail and polling loops

Note: those need an AWS account and aws-cli configured.