copy

How to use the Linux ‘scp’ command without a password to make remote backups

Summary: How to create a public and private key pair to use ssh and scp without using a password, which lets you automate a remote server backup process.

Over the last two years I've ended up creating a large collection of websites and web applications on a variety of Linux servers that are hosted with different companies like GoDaddy and A2 Hosting. I recently embarked on a mission to automate the backup processes for all these sites, and as a result of this effort, I thought I'd share what I've learned here.

Linux/Unix: How to copy a directory and save the date/time file information

If you need to copy a directory on Unix/Linux and want to preserve the date/time information while copying the directory and files, use the -p option to save the date/time information, and the -r option to copy the directory properly. For instance, I just used this cp command to copy a directory named OldDir to a new directory named NewDir, while retaining all of the date/time file information:

Unix find command: How to move a group of files into the current directory

I just bought a bunch of MP3 music files from Amazon, and when I downloaded the zip file they provide onto my Mac, it was a bunch of files in a bunch of subdirectories; not really convenient to work with when you’re trying to import them into iTunes. So I used this Unix find command to move all of the music files from the subdirectories they were scattered in into the root directory that was created when I expanded the zip file:

cd Amazon-Music-Folder
find . -type f -exec mv {} . \;

If you ever need to either copy or move a bunch of files with a single command, I hope this example shows the correct find command syntax for your needs. (If you need to copy the files, use the cp command instead of the mv command.)

How to make a backup copy (ISO) of a CD or DVD using the MacOS dd command

Table of Contents1 - Step 1: Insert a CD or DVD2 - Step 2: Find the CD/DVD identifier3 - Step 3: Unmount the drive4 - Step 4: Copy the DVD with the dd command5 - Step 5: Eject your media

If you want to make a backup copy (an ISO image) of a CD or DVD on a MacOS system using the dd command at the Mac Terminal command line, I’ll demonstrate the process in this tutorial.

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Step 1: Insert a CD or DVD

Assuming that you’re using an external CD/DVD drive, the first step is to connect your drive to your computer, and then insert a CD or DVD. If you insert a movie or music CD and an application automatically starts playing, quit that application.

The beginning of a Scala “FileUtils” class

In production code I recommend that you use a good “Files” library like Apache Commons IO, but if you want to create your own Scala FileUtils class, here’s some source code that can help you get started.

First, here’s some code for the FileUtils class (an object, technically):

A Linux shell script to rename files with a counter and copy them

As a brief note today, I was recently looking for all Messages/iMessage files that are stored on my Mac, and I used this shell script to copy all of those files — many of which have the same name — into a directory named tmpdir, giving them all new names during the copy process:

count=1
for i in `cat myfiles`
do
    fname=`basename $i`
    cp $i tmpdir/${count}-${fname}
    count=`expr $count + 1`
done

This is a page from my book, Functional Programming, Simplified

Scala/FP Idiom: Update as You Copy, Don’t Mutate

“I’ve been imitated so well I’ve heard people copy my mistakes.”

Jimi Hendrix

Goals

In functional programming you don’t modify (mutate) existing objects, you create new objects with updated fields based on existing objects. For instance, last year my niece’s name was “Emily Maness,” so I could have created a Person instance to represent her, like this:

How to copy the macOS Terminal path to the clipboard

If you want to copy the current macOS Terminal path to the clipboard, you can do it with this simple command:

$ pwd | pbcopy

pwd prints the path to STDOUT, and pbcopy reads that and copies it to the macOS clipboard. Once the path is on the clipboard you can paste it into your other applications.

Of course you can also create an alias, like this:

alias path="pwd | pbcopy"

How to copy text from the MacOS Terminal to the clipboard

If you ever need to copy text (or a text file) from the MacOS Terminal to the Mac clipboard, I can confirm that the macOS pbcopy command works. It reads from STDIN and copies the text to the clipboard, so commands like these work:

$ echo "foo bar baz" | pbcopy

$ cat /etc/passwd | pbcopy