{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "detected-assault",
   "metadata": {},
   "source": [
    "# Shell variables"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "b7bce137",
   "metadata": {},
   "source": [
    "## Display of all shell variables"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "civic-porcelain",
   "metadata": {
    "execution": {
     "iopub.execute_input": "2026-05-20T17:59:16.306108Z",
     "iopub.status.busy": "2026-05-20T17:59:16.305936Z",
     "iopub.status.idle": "2026-05-20T17:59:16.434541Z",
     "shell.execute_reply": "2026-05-20T17:59:16.433946Z",
     "shell.execute_reply.started": "2026-05-20T17:59:16.306091Z"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "!=0\n",
      "'#'=0\n",
      "'$'=29997\n",
      "'*'=(  )\n",
      "-=569X\n",
      "0=/bin/zsh\n",
      "'?'=0\n",
      "@=(  )\n",
      "ARGC=0\n",
      "CDPATH=''\n",
      "CLICOLOR=1\n",
      "CLICOLOR_FORCE=1\n",
      "COLUMNS=80\n",
      "CPPFLAGS=-I/opt/homebrew/opt/libomp/include\n",
      "CPUTYPE=arm64\n",
      "EGID=20\n",
      "EUID=501\n",
      "FIGNORE=''\n",
      "FORCE_COLOR=1\n",
      "FPATH=/opt/homebrew/share/zsh/site-functions:/usr/local/share/zsh/site-functions:/usr/share/zsh/site-functions:/usr/share/zsh/5.9/functions:/Users/veit/.zfunc\n",
      "FUNCNEST=700\n",
      "GID=20\n",
      "GIT_PAGER=cat\n",
      "HISTCHARS='!^#'\n",
      "HISTCMD=0\n",
      "HISTSIZE=30\n",
      "HOME=/Users/veit\n",
      "HOMEBREW_CELLAR=/opt/homebrew/Cellar\n",
      "HOMEBREW_NO_ANALYTICS=1\n",
      "HOMEBREW_PREFIX=/opt/homebrew\n",
      "HOMEBREW_REPOSITORY=/opt/homebrew\n",
      "HOST=fay.local\n",
      "IFS=$' \\t\\n\\C-@'\n",
      "INFOPATH=/opt/homebrew/share/info:\n",
      "JPY_PARENT_PID=92198\n",
      "JPY_SESSION_NAME=/Users/veit/cusy/trn/Python4DataScience/docs/workspace/ipython/unix-shell/shell-variables.ipynb\n",
      "KEYBOARD_HACK=''\n",
      "KEYTIMEOUT=40\n",
      "LC_CTYPE=UTF-8\n",
      "LDFLAGS=-L/opt/homebrew/opt/libomp/lib\n",
      "LINENO=1\n",
      "LINES=24\n",
      "LISTMAX=100\n",
      "LOGNAME=veit\n",
      "LaunchInstanceID=3B58B71F-E402-40DE-883C-664B9838C83A\n",
      "MACHTYPE=x86_64\n",
      "MAILCHECK=60\n",
      "MAILPATH=''\n",
      "MANPATH=''\n",
      "MODULE_PATH=/usr/lib/zsh/5.9\n",
      "MPLBACKEND=module://matplotlib_inline.backend_inline\n",
      "NULLCMD=cat\n",
      "OLDPWD=/Users/veit/cusy/trn/Python4DataScience/docs/workspace/ipython/unix-shell\n",
      "OPTARG=''\n",
      "OPTIND=1\n",
      "OSTYPE=darwin24.0\n",
      "PAGER=cat\n",
      "PATH=/Users/veit/cusy/trn/Python4DataScience/.venv/bin:/Users/veit/.local/bin:/Users/veit/.cargo/bin:/Users/veit/spack/bin:/opt/homebrew/opt/ruby/bin:/opt/homebrew//lib/ruby/gems/3.3.0/bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin:/usr/local/MacGPG2/bin:/Library/TeX/texbin:/Users/veit/.lmstudio/bin\n",
      "PPID=29994\n",
      "PROMPT=''\n",
      "PROMPT2=''\n",
      "PROMPT3='?# '\n",
      "PROMPT4='+%N:%i> '\n",
      "PS1=''\n",
      "PS2=''\n",
      "PS3='?# '\n",
      "PS4='+%N:%i> '\n",
      "PSVAR=''\n",
      "PWD=/Users/veit/cusy/trn/Python4DataScience/docs/workspace/ipython/unix-shell\n",
      "PYDEVD_USE_FRAME_EVAL=NO\n",
      "RANDOM=25357\n",
      "READNULLCMD=more\n",
      "SAVEHIST=0\n",
      "SECONDS=0\n",
      "SECURITYSESSIONID=186b1\n",
      "SHELL=/bin/zsh\n",
      "SHLVL=2\n",
      "SPACK_PYTHON=/opt/homebrew/bin/python3\n",
      "SPACK_ROOT=/Users/veit/spack\n",
      "SPROMPT='zsh: correct '\\''%R'\\'' to '\\''%r'\\'' [nyae]? '\n",
      "SSH_AUTH_SOCK=/private/tmp/com.apple.launchd.YA3uoh9GcT/Listeners\n",
      "TERM=xterm-color\n",
      "TERM_PROGRAM=Apple_Terminal\n",
      "TERM_PROGRAM_VERSION=455.1\n",
      "TERM_SESSION_ID=91C8B4C6-9710-438B-BB3A-7AFFCDE0F900\n",
      "TIMEFMT='%J  %U user %S system %P cpu %*E total'\n",
      "TMPDIR=/var/folders/hk/s8m0bblj0g10hw885gld52mc0000gn/T/\n",
      "TMPPREFIX=/tmp/zsh\n",
      "TRY_BLOCK_ERROR=-1\n",
      "TRY_BLOCK_INTERRUPT=-1\n",
      "TTY=/dev/ttys098\n",
      "TTYIDLE=0\n",
      "UID=501\n",
      "USER=veit\n",
      "USERNAME=veit\n",
      "UV=/Users/veit/.local/bin/uv\n",
      "UV_RUN_RECURSION_DEPTH=1\n",
      "VENDOR=apple\n",
      "VIRTUAL_ENV=/Users/veit/cusy/trn/Python4DataScience/.venv\n",
      "WATCH\n",
      "WORDCHARS='*?_-.[]~=/&;!#$%^(){}<>'\n",
      "XPC_FLAGS=0x0\n",
      "XPC_SERVICE_NAME=0\n",
      "ZSH_ARGZERO=/bin/zsh\n",
      "ZSH_EVAL_CONTEXT=cmdarg\n",
      "ZSH_EXECUTION_STRING=set\n",
      "ZSH_NAME=zsh\n",
      "ZSH_PATCHLEVEL=zsh-5.9-0-g73d3173\n",
      "ZSH_SUBSHELL=0\n",
      "ZSH_VERSION=5.9\n",
      "_=set\n",
      "__CFBundleIdentifier=com.apple.Terminal\n",
      "__CF_USER_TEXT_ENCODING=0x1F5:0x0:0x0\n",
      "aliases\n",
      "argv=(  )\n",
      "builtins\n",
      "cdpath=(  )\n",
      "commands\n",
      "dirstack\n",
      "dis_aliases\n",
      "dis_builtins\n",
      "dis_functions\n",
      "dis_functions_source\n",
      "dis_galiases\n",
      "dis_patchars\n",
      "dis_reswords\n",
      "dis_saliases\n",
      "fignore=(  )\n",
      "fpath=( /opt/homebrew/share/zsh/site-functions /usr/local/share/zsh/site-functions /usr/share/zsh/site-functions /usr/share/zsh/5.9/functions /Users/veit/.zfunc )\n",
      "funcfiletrace\n",
      "funcsourcetrace\n",
      "funcstack\n",
      "functions\n",
      "functions_source\n",
      "functrace\n",
      "galiases\n",
      "histchars='!^#'\n",
      "history\n",
      "historywords\n",
      "jobdirs\n",
      "jobstates\n",
      "jobtexts\n",
      "keymaps\n",
      "mailpath=(  )\n",
      "manpath=(  )\n",
      "module_path=( /usr/lib/zsh/5.9 )\n",
      "modules\n",
      "nameddirs\n",
      "options\n",
      "parameters\n",
      "patchars\n",
      "path=( /Users/veit/cusy/trn/Python4DataScience/.venv/bin /Users/veit/.local/bin /Users/veit/.cargo/bin /Users/veit/spack/bin /opt/homebrew/opt/ruby/bin /opt/homebrew//lib/ruby/gems/3.3.0/bin /opt/homebrew/bin /opt/homebrew/sbin /usr/local/bin /System/Cryptexes/App/usr/bin /usr/bin /bin /usr/sbin /sbin /var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin /var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin /var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin /Library/Apple/usr/bin /usr/local/MacGPG2/bin /Library/TeX/texbin /Users/veit/.lmstudio/bin )\n",
      "pipestatus=(  )\n",
      "prompt=''\n",
      "psvar=(  )\n",
      "reswords\n",
      "saliases\n",
      "signals=( EXIT HUP INT QUIT ILL TRAP ABRT EMT FPE KILL BUS SEGV SYS PIPE ALRM TERM URG STOP TSTP CONT CHLD TTIN TTOU IO XCPU XFSZ VTALRM PROF WINCH INFO USR1 USR2 ZERR DEBUG )\n",
      "status=0\n",
      "termcap\n",
      "terminfo\n",
      "userdirs\n",
      "usergroups\n",
      "watch\n",
      "widgets\n",
      "zsh_eval_context=( cmdarg )\n",
      "zsh_scheduled_events\n"
     ]
    }
   ],
   "source": [
    "!set"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "modified-eagle",
   "metadata": {},
   "source": [
    "## Showing the value of a variable"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "focused-pastor",
   "metadata": {
    "execution": {
     "iopub.execute_input": "2026-05-20T17:59:16.435466Z",
     "iopub.status.busy": "2026-05-20T17:59:16.435285Z",
     "iopub.status.idle": "2026-05-20T17:59:16.563027Z",
     "shell.execute_reply": "2026-05-20T17:59:16.562119Z",
     "shell.execute_reply.started": "2026-05-20T17:59:16.435444Z"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "/Users/veit\n"
     ]
    }
   ],
   "source": [
    "!echo $HOME"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "valued-coach",
   "metadata": {},
   "source": [
    "## The `path` variable\n",
    "\n",
    "It defines the shell’s search path, i.e., the list of directories that the shell looks in for runnable programs."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "victorian-consensus",
   "metadata": {
    "execution": {
     "iopub.execute_input": "2026-05-20T17:59:16.564494Z",
     "iopub.status.busy": "2026-05-20T17:59:16.564245Z",
     "iopub.status.idle": "2026-05-20T17:59:16.690874Z",
     "shell.execute_reply": "2026-05-20T17:59:16.689923Z",
     "shell.execute_reply.started": "2026-05-20T17:59:16.564472Z"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "/Users/veit/cusy/trn/Python4DataScience/.venv/bin:/Users/veit/.local/bin:/Users/veit/.cargo/bin:/Users/veit/spack/bin:/opt/homebrew/opt/ruby/bin:/opt/homebrew//lib/ruby/gems/3.3.0/bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/Library/Apple/usr/bin:/usr/local/MacGPG2/bin:/Library/TeX/texbin:/Users/veit/.lmstudio/bin\n"
     ]
    }
   ],
   "source": [
    "!echo $PATH"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "personal-stream",
   "metadata": {},
   "source": [
    "## Creating and changing variables"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "sweet-function",
   "metadata": {},
   "source": [
    "### Creating or overwriting variables"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "abandoned-reservation",
   "metadata": {
    "execution": {
     "iopub.execute_input": "2026-05-20T17:59:16.692570Z",
     "iopub.status.busy": "2026-05-20T17:59:16.692110Z",
     "iopub.status.idle": "2026-05-20T17:59:16.818652Z",
     "shell.execute_reply": "2026-05-20T17:59:16.817922Z",
     "shell.execute_reply.started": "2026-05-20T17:59:16.692547Z"
    }
   },
   "outputs": [],
   "source": [
    "!export SPACK_ROOT=~/spack"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "varying-muscle",
   "metadata": {},
   "source": [
    "### Append additional specifications"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "premier-career",
   "metadata": {
    "execution": {
     "iopub.execute_input": "2026-05-20T17:59:16.819820Z",
     "iopub.status.busy": "2026-05-20T17:59:16.819635Z",
     "iopub.status.idle": "2026-05-20T17:59:16.941086Z",
     "shell.execute_reply": "2026-05-20T17:59:16.940406Z",
     "shell.execute_reply.started": "2026-05-20T17:59:16.819799Z"
    }
   },
   "outputs": [],
   "source": [
    "!export PATH=/usr/local/opt/python@3.13/bin:$PATH"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3.13 Kernel",
   "language": "python",
   "name": "python313"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.13.0"
  },
  "latex_envs": {
   "LaTeX_envs_menu_present": true,
   "autoclose": false,
   "autocomplete": true,
   "bibliofile": "biblio.bib",
   "cite_by": "apalike",
   "current_citInitial": 1,
   "eqLabelWithNumbers": true,
   "eqNumInitial": 1,
   "hotkeys": {
    "equation": "Ctrl-E",
    "itemize": "Ctrl-I"
   },
   "labels_anchors": false,
   "latex_user_defs": false,
   "report_style_numbering": false,
   "user_envs_cfg": false
  },
  "widgets": {
   "application/vnd.jupyter.widget-state+json": {
    "state": {},
    "version_major": 2,
    "version_minor": 0
   }
  }
 },
 "nbformat": 4,
 "nbformat_minor": 5
}