A simple bash program to open a shell in a temporary directory (~/.tmp) by default and remove the directory after the shell closes.

tmpsh

#!/usr/bin/env bash
set -euC -o pipefail
user_shell=$SHELL # This is the user's login shell, or the path to bash if unset. This is usually set by login.
_TMPDIR=~/.tmp

this=${BASH_SOURCE[0]:-$0}
this=${this##*/} # this is the name of the script without the path

log() { printf '%s\n' "$@" || true; }
err() { printf 'Error: %s\n' "$@" 2>&1 || true; }
diag() {
  [ -t 2 ] || return # if stderr is not a terminal, don't print diagnostics
  printf '%s\n' "$@" >&2 || true
}
abort() { err "$1" && exit "${2:-1}"; }

# check for the --help flag (before --)
# this is just for user experience, since technically only one argument is allowed
# if the user specifies `tmpsh dir --help`, we want to print the help message and exit
for arg; do
  case "$arg" in
  -h | --help)
    tildified=${_TMPDIR/#"$HOME/"/"~/"} # replace $HOME/ with ~/ at the beginning of the path
    log "Usage: $this [directory]" \
      "Creates a new temporary directory (defaults to $tildified/$this), then opens an interactive shell in it." \
      "Prompts to remove the directory after the shell exits." \
      "" \
      "Options:" \
      "  -h, --help    Print this help message and exit"
    exit 0
    ;;
  --) break ;;
  esac
done
[ "${1:-}" != "--" ] || shift                  # skip the first argument if it is --
[ "$#" -le 1 ] || abort "Too many arguments" 2 # only one argument is allowed
dir="${1:-}"

# If a directory is specified, create it, then use it. Fail if it already exists.
# Otherwise, create a temporary directory in "$DEFAULT_TMP_DIR"/tmpsh, counting up from 1 if it already exists.
if [ -n "$dir" ]; then
  if [ -d "$dir" ]; then abort "Directory $dir already exists." 2; fi
  mkdir -- "$dir" || abort "Could not create directory $dir." "$?"
else
  mkdir -p -- "$_TMPDIR" || abort "Could not create directory $_TMPDIR" "$?"
  # Sanity check: make sure "$DEFAULT_TMP_DIR" is writable. Otherwise, all the mkdirs will fail and we'll loop forever.
  # technically a race condition, but better to fail than loop forever
  [ -w "$_TMPDIR" ] || abort "Cannot make directories in "$_TMPDIR"" 1
  base="$_TMPDIR"/$this dir=$base
  if ! mkdir -- "$dir" 2>/dev/null; then
    n=1
    until mkdir -- "${dir:=$base-$n}" 2>/dev/null; do
      n=$((n + 1))
      dir=                                        # ensure that the above assignment is re-evaluated
      [ -d "$_TMPDIR" ] || mkdir -p -- "$_TMPDIR" # just in case it was removed between mkdirs
    done
  fi
fi
[ -d "$dir" ] || abort "Somehow $dir was not created! This is probably a bug in $this." 3

# Not an error, but warn the user if they are in a temporary shell
[ -z "${TMPSH:-}" ] || diag "Warning: already in a temporary shell!"
export TMPSH=1 # Indicate that we're in a temporary shell

diag "Entering temporary directory $dir"
# Use pushd/popd in case the directory is relative
pushd -- "$dir" >/dev/null
# preserve the shell exit code
exit_code=0
# Lie about the shlvl since it doesn't make sense to count this shell as a subshell
SHLVL=$((SHLVL - 1)) "$user_shell" || exit_code=$?
popd >/dev/null
diag "Leaving temporary directory $dir"

# Try to remove the directory, if empty
if ! rmdir -- "$dir" 2>/dev/null; then
  # the directory is not empty, so try to remove it recursively (after prompting)
  # If tree is present, use it to print the directory structure; otherwise fall back to ls
  if command -v tree >/dev/null; then
    tree -a -F -L1 -- "$dir"
  else
    if ls --help 2>&1 | grep -q -- --color; then
      ls -A --color -F -- "$dir"
    else
      ls -a -F -- "$dir"
    fi
  fi
  # if the user aborts, don't delete the directory
  read -rp "$this: remove directory '$dir'? [Y/n] " yn || yn=n
  case "${yn,,}" in # note: this follows 'rm' semantics, anything begining with 'y' is true
  y* | "") rm -fr -- "$dir" ;;
  *) # Don't delete work, but warn the user that this should be moved to a long-term storage
    diag "Leaving temporary directory $dir"
    diag "You must remove it manually or it will not be reused!"
    diag "If you want to keep the directory, you should move it to another location."
    ;;
  esac
fi
case "$dir" in                                           # if directory is a subdirectory of $DEFAULT_TMP_DIR
"$_TMPDIR"/*) rmdir -- "$_TMPDIR" 2>/dev/null || true ;; # remove the temporary directory if it is empty
esac

# preserve the shell exit code
exit "$exit_code"