Creating, Copying, Moving, and Removing Content

1. mkdir -p expresses a convergent directory goal

workspace="$HOME/builds/api"
mkdir -p -- "$workspace"

This is generally better than checking for existence and then creating the directory in a separate step.

2. Copy semantics depend on the destination

cp -- source.conf backup.conf
cp -- artifact.tar.gz releases/

A directory destination preserves the source basename; a file destination names the new copy. Scripts should know which interpretation they require.

3. Recursive copy requires explicit testing

mkdir -p config-live
cp -R -- config-template/. config-live/

The exact source spelling can change whether the directory itself or only its contents are copied.

4. Make overwrite policy explicit

if [[ -e $destination ]]; then
  printf 'destination exists: %s\n' "$destination" >&2
  exit 1
fi
cp -- "$source" "$destination"

Interactive confirmation flags are not a reliable non-interactive automation policy.

5. mv is useful for promotion

mv -- staged.conf live.conf

Within one filesystem, rename-like moves can efficiently switch pathname references. Cross-filesystem moves may require copy-and-remove behavior instead.

6. rm deserves stronger validation than ordinary commands

target="$workspace/cache"

if [[ -z $target || $target == / ]]; then
  printf 'refusing dangerous target\n' >&2
  exit 1
fi

rm -rf -- "$target"

7. Constrain deletion to a managed root

root="$HOME/devops-academy/work"
target="$root/cache"

case $target in
  "$root"/*) rm -rf -- "$target" ;;
  *) printf 'outside managed root\n' >&2; exit 1 ;;
esac

This is a useful policy check but not a complete defense against all symlink/canonicalization issues.

8. install combines copying with mode management

install -d -m 0755 -- "$HOME/.local/bin"
install -m 0755 -- deployctl "$HOME/.local/bin/deployctl"

This can make packaging-style operations clearer than a copy followed by a separate chmod.

9. Destructive workflows benefit from dry-run

remove_path() {
  local target=$1
  if [[ $dry_run == true ]]; then
    printf 'DRY-RUN: rm -rf -- %q\n' "$target"
  else
    rm -rf -- "$target"
  fi
}

Dry-run must bypass the real mutation.

10. Hands-on lab: stage and promote content

mkdir -p "$HOME/devops-academy/bash/chapter09/lesson02"
cd "$HOME/devops-academy/bash/chapter09/lesson02"

rm -rf -- staging live live.new live.old
mkdir -p -- staging live

printf 'version=2\n' > staging/app.conf
printf 'feature=true\n' > staging/feature.conf

mkdir -- live.new
cp -R -- staging/. live.new/

mv -- live live.old
mv -- live.new live

printf '%s\n' '--- live files ---'
find live -maxdepth 1 -type f -print

rm -rf -- live.old

11. Knowledge check

12. Summary

Filesystem mutation should be explicit about destinations, recursion, overwrite, and deletion. Prefer staging, validated destructive roots, quoted operands, idempotent directory creation, and real dry-run behavior.

13. Further reading

• GNU Coreutils manuals — mkdir, cp, mv, rm, install.
• POSIX filesystem utility specifications.
• rsync documentation for tree synchronization.
• ShellCheck documentation — destructive path handling.