Creating, Copying, Moving, and Removing Files

1. A filesystem operation has a target and a consequence

Commands such as cp, mv, and rm look simple, but their effect depends on pathname resolution, whether a destination exists, shell expansion, permissions, filesystem boundaries, and command options. Reliable operators make those conditions visible before changing state.

flowchart TD
  I["Identify source and destination"] --> P["Print working directory and preview paths"]
  P --> C["Choose explicit command options"]
  C --> E["Execute one bounded operation"]
  E --> V["Verify names, type, size, and content"]
  V --> R["Retain backup or rollback path"]

2. Create directories and files deliberately

mkdir creates directories. Without -p, it fails when a required parent is missing or when the target already exists. With -p, it creates missing parents and treats an existing directory as success.

workspace="$HOME/devops-academy/linux/chapter04/lesson01"
mkdir -p -- "$workspace"/{source,staging,archive}

# Create a file with known content rather than an ambiguous empty placeholder.
printf '%s\n' 'service_name=demo-api' 'port=8080' > "$workspace/source/app.conf"

# Create an empty marker only when emptiness is the intended state.
touch -- "$workspace/source/.initialized"

printf 'Created workspace:\n'
find "$workspace" -maxdepth 2 -printf '%y %p\n' | sort

The separator -- ends option parsing for commands that support it. A filename beginning with - is then treated as an operand rather than an option. Quoting variables preserves spaces and prevents unintended splitting and glob expansion.

3. Copy with explicit overwrite and metadata intent

cp SOURCE DESTINATION copies file data. When the destination names an existing directory, the source basename is placed inside that directory. When the destination is a non-directory pathname, it becomes the new name. This distinction is a common source of mistakes.

cd -- "$workspace"

# Copy one file to a new pathname. -v reports the operation.
cp -v -- source/app.conf staging/app.conf

# Refuse to overwrite an existing file.
cp -vn -- source/app.conf staging/app.conf

# Preserve mode, ownership when permitted, timestamps, and links for a tree.
cp -a -- source/. staging/source-snapshot/

# Compare copied content.
cmp -- source/app.conf staging/app.conf && printf 'content matches\n'

For deployment automation, never depend on a shell alias such as cp='cp -i'. Scripts run in different environments. State every required option in the script and validate the destination independently.

4. Move and rename: same command, different mechanics

mv renames or relocates filesystem entries. Within one filesystem, a move is often a metadata operation: the directory entry changes while file data remains in place. Across filesystems, the implementation generally copies data and then removes the source after a successful copy.

cd -- "$workspace"

# Rename within one directory.
mv -v -- staging/app.conf staging/app.conf.candidate

# Move into an existing directory.
mv -v -- staging/app.conf.candidate archive/

# Refuse to overwrite an existing destination.
mv -vn -- source/app.conf archive/app.conf

# Verify the final locations.
find source staging archive -maxdepth 2 -printf '%y %p\n' | sort

5. Removal unlinks names; it does not provide a recycle bin

rm removes directory entries. A normal command-line environment does not move them to a graphical trash folder. Recovery may be difficult or impossible, especially after storage blocks are reused. The safest removal is one whose exact target set was already printed and reviewed.

target="$workspace/staging/source-snapshot"

# Preview the exact tree first.
printf 'Candidate removal tree:\n'
find "$target" -depth -printf '%y %p\n'

# Require the expected parent path before removal.
case "$target" in
  "$HOME/devops-academy/linux/chapter04/lesson01/staging/"*)
    rm -r -- "$target"
    ;;
  *)
    printf 'Refusing unexpected target: %s\n' "$target" >&2
    exit 64
    ;;
esac

# Remove an empty directory with the narrower command.
rmdir -- "$workspace/staging"

6. Safer patterns for interactive and automated work

7. Hands-on lab: assemble and publish a release directory

This lab creates a miniature release workspace, builds a candidate directory, verifies it, publishes it through a rename, and removes only a disposable build area.

set -u
root="$HOME/devops-academy/linux/chapter04/lesson01-release"
source_dir="$root/source"
build_dir="$root/build/release-1.0.0"
releases_dir="$root/releases"

mkdir -p -- "$source_dir" "$build_dir" "$releases_dir"
printf '%s\n' '<h1>DevOps Academy demo</h1>' > "$source_dir/index.html"
printf '%s\n' 'version=1.0.0' > "$source_dir/release.env"

cp -a -- "$source_dir/." "$build_dir/"
printf '%s  %s\n' \
  "$(sha256sum "$build_dir/index.html" | awk '{print $1}')" \
  'index.html' > "$build_dir/SHA256SUMS"

# Verify required files before publication.
for required in index.html release.env SHA256SUMS; do
  test -f "$build_dir/$required" || {
    printf 'missing required file: %s\n' "$required" >&2
    exit 1
  }
done

published="$releases_dir/1.0.0"
test ! -e "$published" || {
  printf 'release already exists: %s\n' "$published" >&2
  exit 1
}
mv -- "$build_dir" "$published"

printf 'Published release:\n'
find "$published" -maxdepth 1 -type f -printf '%f\n' | sort

# Remove only the now-empty build parent.
rmdir -- "$root/build"
printf 'Workspace retained at %s\n' "$root"

8. Common file-operation mistakes

9. Knowledge check

10. Summary

Controlled file operations begin with explicit paths and end with verification. mkdir and printf create structure and content; cp duplicates data; mv renames or relocates entries; rm and rmdir unlink names. No-clobber options, bounded targets, staging directories, and rollback paths turn fragile commands into operational procedures.

11. Further reading

• GNU Coreutils manuals for mkdir, touch, cp, mv, rm, rmdir, install, and sha256sum.
• Linux manual pages for rename, unlink, open, stat, and path_resolution.
• POSIX specifications for cp, mv, rm, mkdir, and pathname handling.
• Filesystem Hierarchy Standard — placement and purpose of system directories.
• GNU Bash Reference Manual — quoting, expansion, exit status, and command execution.