Bash - 09 - File Movement and Copy Commands

Naming Conventions

• Avoid spaces; use _ or - instead.
• Do not start names with - to prevent confusion with options/flags.
• Stick to characters: 0-9, a-z, ., -, _. Special characters can have different meanings.
• Use single quotes ' ' for names with spaces or special characters.

File Movement and Copy Command

Moving / Renaming (mv), copying (cp), creating, deleting (rm) files and directories.
These work by modifying the directory entries of the files they access.

• cp adds an entry to the directory with the name of destination file and inode number that is allotted by the kernel.
• mv replaces the name of an existing directory entry without disturbing its inode number.
• rm removes an entry from the directory.

mv

mv is used to move or rename both files and directories.

mv [options] source destination

To rename a file, source is the old name and destination is the new name. Otherwise, both need to be in different directories. If destination is a directory without a file name, the file’s name is not changed.

mv fo1.txt ~/temp
# moves to temp

mv fo1.txt ~/temp/fo2.txt
# moves and renames

mv *.txt /home/zapp

To move a file into the current directory, . can be used as the destination.

Renaming Files To rename a file or move it to a new location:

mv [old] [new]  # Moves or renames a file

mv trial/draft.txt trial/quotes.txt  
# Renames draft.txt to quotes.txt

mv draft.txt quotes.txt
# Renames within the same directory

Note: Moving a file to a directory with the same name will silently overwrite the original. Use mv -i to prompt for confirmation.

To move files to a different directory:

mv trial/quotes.txt .  
# Moves to the current directory

mv sucrose.dat maltase.dat ../raw  
# Moves files to the parent directory's raw folder

We are not allowed to rename multiple files using a single mv command as it has only a single destination parameter. mv *.txt *.dat will cause an error because *.dat means multiple destinations, but it needs to be a single directory or file name.

-i and -f are interactive and force modes. The difference occurs when a file being moved has the same name at the destination. If not interactive, the destination file is overwritten.

cp

The format is the same as mv:

cp [options] source destination

cp [old] [new]  # Copies a file

cp quotes.txt thesis/quotation.txt  
# Copies to a new location

There are three combinations that can be used:

• Destination is another directory, then the file name remains the same after copying.
• Destination is a directory and a file name, then the file is copied with a new name.
• Destination is a filename, then the file is copied into the current directory with a new name.

cp fo.txt ~zap/fo1.txt
cp *.txt ~
cp ~zapp/foo.txt .

-i and -f remain the same as mv.

• -b: Creates a backup of every destination file.
• -I/-s: Creates a hard or symbolic link rather than a physical copy.
• -u: Copies only if the source is newer than the destination or if the destination is missing.
• -L: If the source is a symbolic link, it follows the link to the actual file and copies that file, not the link.
• -v: Provides output for each file copied. (verbose)
• -p: Preserves the original ownership, permissions, and timestamps. (When cp creates a copy, it’s ownership and permissions are updated to that pf the user who issued the command.)
• -r: Recursive copy for directories and their contents.

To copy a directory and all its contents, use -r:

cp -r thesis thesis_backup  
# Copies the entire directory

Operations with Multiple Files and Directories

To copy or move multiple files, list the files followed by the target directory. If given more than one file name followed by a directory name, the directory must be the last argument.

cp file1.txt file2.txt target_directory/  
# Copy multiple files

mv file1.txt file2.txt target_directory/   
# Move multiple files

Using wildcards simplifies this process:

cp *.txt backup/  # Copies all .txt files to backup/

$ mkdir backup

$ cp cretures/minotaur.dat creatures/unicorn.dat backup/

$ cp minotaur.dat unicorn.dat basilisk.dat
# Error occurs with multiple files; use wildcards instead

Wildcards

Wildcards represent unknown characters in commands.

Common wildcards include:

*: Represents zero or more characters.

• *.pdb matches all files ending with .pdb.
• *ethane.pdb matches ethane and methane.
• p*.pdb matches files starting with p and ending with .pdb.

?: Represents exactly one character.

• ?ethane.pdb matches methane.pdb.

Using Wildcards in Commands

ls *t*ane.pdb   
# Lists files with 't' and 'ane' in their names

cp *dataset* backup/datasets  
# Copies all files with 'dataset' in the name

ls *t?ne.*     # matches octane, pentane
ls *t??ne.pdb  # matches ethane, methane
ls ethane.*    # only ethane

Wildcards can be combined for more specific patterns:

ls ???ane.pdb  
# Matches any three characters followed by 'ane.pdb'

When a shell sees a wildcard, it expands the wildcard to create a list of matching filenames before running the preceding command.

Note: Be cautious when using wildcards, as errors can occur if not handled properly (e.g., *.pdf in a directory with .pdb files).

Using Wildcards for Copying

$ cp *dataset* backup/datasets
# Copy anything with 'dataset' in the name to the datasets directory inside backups

$ cp *calibration.txt backup/calibration
# Copy all calibration files

$ cp 2015-11-* send_to_bob/all_november_files/
# Copy just November files

$ cp *-23-dataset* send_to_bob/all_datasets_created_on_23rd/
# Copy only 23rd files

rm

rm is the delete command.

rm [options] file(s)

It can work on multiple files by listing, using wildcards, or both.

rm my_file.txt  
# Deletes the specified file

Use rm -i to prompt for confirmation before deletion. rm permanently deletes files, so it’s advisable to use -i to ask for confirmation before deleting. The alias for rm can be set as rm -i

If too many files are being deleted and you want to override the prompts, use -f, but this can be dangerous: rm -f *.txt.

rm cannot remove directories directly. To remove a directory and its contents, use the recursive -r option:

rm -r directory_name  
# Deletes the directory and all its contents

To delete a complete sub-hierarchy and override the prompts, use rm -fr *.

• To remove files matching a pattern (e.g., all .txt files) with confirmation:

rm -i *.txt  # Prompts for each .txt file

Note: The shell does not have a trash bin, so deleted files are permanently removed.

rmdir is the only way to delete an empty directory. Use rmdir -p to recursively delete parent and current directories.

mkdir Creating Directories

Used to create a directory, in the current directory or a specified path.

• -m --mode: Specify the initial permissions of the directory.
• -z --context: Specify the SELinux context.

mkdir [name]  # Create a directory

To create multiple directories at once:

mkdir north south pacific  
# Creates three separate directories

Creating a Directory Tree, by creating the main directory first, then child directories inside.

mkdir place place/one place/two

The -p option is used to create multiple directories at once:

mkdir -p [path/to/nested/directories]  
# Creates nested directories

mkdir -p ../project/data ../project/results

To list all nested subdirectories within a directory, use ls -R.

Example:

To create a directory 2016 with a sub-directory data that contains two directories, processed and raw:

Method 1: Step-by-Step Creation

mkdir 2016
mkdir 2016/data
mkdir 2016/data/processed
mkdir 2016/data/raw

Method 2: Navigating and Creating

mkdir 2016
cd 2016
mkdir data
cd data
mkdir processed raw

Method 3: Using -p

mkdir -p 2016/data/{processed,raw}  
# Creates the full structure in one command