{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Unix Essentials — Bash Exercises\n",
    "\n",
    "This notebook contains short hands-on Bash exercises.\n",
    "Each exercise has a hidden solution that can be unfolded when needed."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exercise 1 – Listing and Filtering Files\n",
    "\n",
    "Create three files and list only those whose name ends with `.log`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# your work here\n",
    "touch report.log notes.txt errors.log\n",
    "# list files ending with .log"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "jupyter": {
     "source_hidden": true,
     "outputs_hidden": true
    }
   },
   "outputs": [],
   "source": [
    "# Solution\n",
    "ls *.log"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exercise 2 – Redirecting Output\n",
    "\n",
    "List the `/etc` directory and save the results in a file named `listing.txt`, then display the first five lines of that file."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# your work here\n",
    "# 1. list /etc\n",
    "# 2. redirect output to listing.txt\n",
    "# 3. show first five lines"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "jupyter": {
     "source_hidden": true,
     "outputs_hidden": true
    }
   },
   "outputs": [],
   "source": [
    "# Solution\n",
    "ls /etc > listing.txt\n",
    "head -5 listing.txt"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exercise 3 – Using a For Loop\n",
    "\n",
    "Write a loop that prints the line count of each `.txt` file in the current directory."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# your work here\n",
    "# hint: use wc -l"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "jupyter": {
     "source_hidden": true,
     "outputs_hidden": true
    }
   },
   "outputs": [],
   "source": [
    "# Solution\n",
    "for f in *.txt; do\n",
    "  echo \"$f: $(wc -l < \"$f\") lines\"\n",
    "done"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "---\n",
    "All solutions are hidden by default (`source_hidden: true`). Students can unfold them in Jupyter’s interface to compare with their own answers."
   ]
  }
 ],
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