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Bulk Rename Files by Pattern

Renames many files at once using a sed substitution, with dry-run preview.

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This script renames many files in one pass by applying a sed substitution expression to each filename, with a safe dry-run as the default. It takes a directory, a sed expression like 's/ /_/g' (replace spaces with underscores) or 's/\.jpeg$/.jpg/' (normalize extensions), and an optional --apply flag. After set -euo pipefail, it validates the directory and enables nullglob so an empty folder produces no spurious iterations. For each regular file it computes the new name via sed -E, skips files whose name is unchanged, and either previews or performs the move. Crucially it uses mv -n so an existing target is never silently clobbered, and -- so filenames beginning with a dash are handled safely. Run it as ./bulk_rename.sh ./pics 's/ /_/g' to preview, then add --apply. Example:

[DRY RUN] my photo.jpg -> my_photo.jpg
[DRY RUN] 1 file(s) would be renamed. Add --apply to commit.

Script

Download .sh

bash

#!/usr/bin/env bash
#
# bulk_rename.sh - Rename multiple files using a sed-style substitution.
#
# Applies a 's/old/new/' transform to filenames in a directory, with a
# dry-run by default so you can preview before committing.
#
# Usage: ./bulk_rename.sh <dir> '<sed_expr>' [--apply]
#
#   sed_expr  e.g. 's/ /_/g'  or  's/\.jpeg$/.jpg/'
#   --apply   perform the rename; otherwise only preview
#
set -euo pipefail

# --- Argument handling --------------------------------------------------------
if [[ $# -lt 2 || $# -gt 3 ]]; then
    echo "Usage: $0 <dir> '<sed_expr>' [--apply]" >&2
    echo "Example: $0 ./pics 's/ /_/g' --apply" >&2
    exit 1
fi

DIR="$1"
SED_EXPR="$2"
APPLY=0
[[ "${3:-}" == "--apply" ]] && APPLY=1

[[ -d "$DIR" ]] || { echo "Error: '$DIR' is not a directory." >&2; exit 1; }

# --- Iterate over files safely ------------------------------------------------
shopt -s nullglob   # an empty directory yields no iterations instead of '*'
RENAMED=0

for path in "$DIR"/*; do
    [[ -f "$path" ]] || continue          # skip subdirectories
    name="$(basename "$path")"
    newname="$(printf '%s' "$name" | sed -E "$SED_EXPR")"

    # Nothing to do if the name is unchanged.
    [[ "$name" == "$newname" ]] && continue

    target="$DIR/$newname"
    if (( APPLY )); then
        # -n (no-clobber) prevents silently overwriting an existing target.
        mv -n -- "$path" "$target"
        echo "Renamed: $name -> $newname"
    else
        echo "[DRY RUN] $name -> $newname"
    fi
    RENAMED=$((RENAMED + 1))
done

if (( APPLY )); then
    echo "Done. $RENAMED file(s) renamed."
else
    echo "[DRY RUN] $RENAMED file(s) would be renamed. Add --apply to commit."
fi

How to run

Review the script first, then download or copy it and run it in your environment.

#Linux #Bash #Automation #Backup #Files #Text Processing

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bashlinuxIntermediate

Bulk Rename Files by Pattern

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How to run

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