Bash script is throwing the error of "missing operand" when ran

Question

I am new to bash and am attempting to take in 2 arguments, and Argument 1 is the name of the new directory where the copied file will go. Argument 2 is the file to be copied. Argument 3 is the name of the new file. However, I keep getting the mkdir missing operand error message when running it. Thank you for any help!!

    #!/bin/bash
    dir=$1
    oldFile=$2
    newFile=$3
    mkdir $dir
    cp $2 $dir
    cd $dir
    mv $2 $3

Answer 1

BRAND NEW, this version covers all cases...

#!/bin/bash

# Verify number of arguments
if [[ $# -ne 3 ]]
then
    echo "Missing arguments."
    echo "1: new directory name"
    echo "2: existing file to copy in the directory"
    echo "3: new filename"
    exit 1
fi

# Verify arguments values
dir="$1"
if [[ -d "$dir" ]]
then
    echo "Directory $dir already exists.  Cannot proceed."
    exit 2
fi

oldfile="$2"
if [[ ! -f "$oldfile" ]]
then
    echo "The second arguments must be an existing file.  Cannot procees."
    exit 3
fi

newfile="$3"
# no check to do here.

# Create the directory
mkdir "$dir"
if [[ ! -d "$dir" ]]
then
    echo "ERROR: directory $dir could not be created.  Aborting."
    exit 4
else
    echo "INFO: created directory $dir"
fi

# Copy the file into the directory, with the new name
cp "$oldfile" "$dir/$newfile"
if [[ ! -f "$dir/$newfile" ]]
then
    echo "ERROR: the existing file ($oldfile) could not be copied and renamed ($newfile)."
    exit 5
else
    echo "INFO: the existing file ($oldfile) was copied and renamed ($newfile) in the $dir directory."
fi

This script:

• verifies if the number of arguments is ok
• verifies if the directory already exists
• verifies that the old file does exist
• verifies that the directory creation and copy-rename of the file completed successfully

Remember to:

• always " your variables
• always check the status of your script commands, you never know what happens in all cases
• be super prudent with rm, mv, you can loose things if you have an unexpected behavior.

To call the script:

./thescript.bash newdirectory oldfilename newfilename

It will give you the files-directory structure:

$ ls
oldfile
newdirectory/newfilename