WP-CLI and The Shell

These are the slides from a talk I did for WordCamp Santa Clarita Valley 2019. Had a blast meeting new friends and learning about the inner workings of WordPress. Can’t wait to attend more! WordCamps are like traveling… Once you start, you’ve got the bug 🙂

The talk was done by parsing a markup file with a custom WP-CLI command. It can be found here:
https://github.com/ecotechie/wp-cli-present-command

The markup file can be found at this repo:
https://github.com/ecotechie/word-camp-santa-clarita-valley-2019

This is how WordPress parses the markdown:

The command line is your friend: WP-CLI, the shell and what they can do for you!

Sergio Scabuzzo – Twitter/@ecotechie – WordCamp Santa Clarita Valley 2019

Who is this guy?

  • Linux user
  • Sustainability warrior
  • WordPress Core and WP-CLI contributor
  • Founder of EcoTechie.io
  • Brewer of things
  • VW bus owner/mechanic

First Things First

With great power comes great responsibility!

The command line takes no prisoners.
If you have a typo or miss something in the logic of your command or script, it can come back to bite you!!!

Don’t blindly copy/paste commands off of the internet before knowing what they do.
Including from these slides.

With that out of the way, let’s get rolling…

Command Line Usage


Why use the command line:

  • Your friends will think you are the coolest 🙂
  • It’s been around (No bugs)
  • Script writing makes many commands work together
  • Repetitive tasks take seconds not minutes, or even hours

Why NOT use the command line:

  • Your friends will think you are a dork 🙁
  • A single command can easily break things if you aren’t careful
  • Script writing makes breaking even more things super easy
  • You can spend hours writing a script that won't get used

Bash and The Easy Stuff

Some common/useful commands:

pwd Print Working Directory

$ pwd
/home/sergio  

mkdir Make directories

cd Change Directory

ls List a directory

cat Show a file’s content

man System’s manual pager
Use it to find information on installed programs, utilities or functions


You Have Options, With Commands

Some handy ls options are:

ls -a do not ignore entries starting with a ., AKA show hidden files and directories
ls -l use a long listing format, AKA verbose
ls -lh with -l to print human readable sizes (e.g., 1K 234M 2G)

Jump around directories with:

cd - change to previous directory
cd use it by itself to change to your home directory


More Advanced Features of the Command line

Remove files or directories

rm -rf !(file1|file2)

What does all that do?

-r, -R, --recursive remove directories and their contents recursively
-f, --force ignore nonexistent files and arguments, never prompt
!() negates whatever is in the parentheses

$ touch file{1..5}
$ ls
file1  file2  file3  file4  file5
$ rm -rf !(file1|file2)
$ ls
file1 file2                       

AKA, Aliases

Sometimes you want to reuse a complicated/convoluted command often enough.

That’s where aliases become very handy.

Add this line to the bottom of your ~/.bashrc file so it persists across reboots.

The ~ represents your home directory.

alias getpass='openssl rand -base64 20'

Why type sudo all the time? No more of that, by creating corresponding aliases.

alias apt-get='sudo apt-get'

WP-CLI for the Easy Win


WordPress Command Line Interface:

“The project’s goal is to offer a complete alternative to the WordPress admin”
“For any action you might want to perform in the WordPress admin, there should be an equivalent WP-CLI command.”

When these actions become scriptable we can start to really see the power of the command line!


Often Used commands

Backup you database, export a .sql file.

wp db export

Regenerate all missing thumbnails for attached images.

wp media regenerate --yes --only-missing

Verify file integrity by comparing to published checksums.

wp checksum core && wp checksum plugin --all

Fix Broken Update

Got a broken update?
White Screen of Death?
Don’t want to update to the latest version?

wp plugin update slug --version=x.x.x

If that doesn’t fix it…

wp plugin deactivate slug

Really tired of this plugin causing trouble?

wp plugin uninstall slug --deactivate

Update Password

Have you ever forgotten your WordPress password?

How do we get back in?

  1. Click on the “Forgot Password” link
  2. Enter email or username
  3. Wait for email and click on the password reset link
  4. Reset Password
  5. Finally login again Or…
  6. SSH into Server
  7. Go to the WordPress Directory wp user update [email protected] –user_pass=C00lP4ssw0rd
We could even use our handy bash alias from earlier and create a more robust password:
getpass
G3Rni/ruEWMoz0U86Ow1gkkoQDQ=  

Create a Child Theme

Ever edit a theme’s code? Only to have your changes erased by the next update…

Let’s create a child theme from the (non-child) active one, then activate it:
wp scaffold child-theme slug --parent_theme=$(wp theme list --status=active --field=name) --activate

What’s happening here?

The $() is known as command substitution

Bash performs the expansion by executing the command inside the parentheses in a subshell environment.
Then replacing the command substitution with the standard output of that command.

This is one of the magic tricks of WP-CLI

Commands should be composable... The output from one command should be easily pipe-able to another command.


So Many Themes, so Little Time

Cleaning up over 132 installed themes?

Some of your options:
  1. Remove the unused themes one by one from the WordPress admin.
  2. Login through (S)FTP and remove all the disabled theme directories.
  3. Use WP-CLI and delete all inactive themes in seconds! wp theme delete $(wp theme list –status=inactive –field=name)

Search for This and Replace with That

What’s this fun thing?

wp search-replace something_old something_new —report-changed-only —dry-run

Let’s do a demo #FamousLastWords…


Create a link on “Hello World”


Sub Demo! Changing Permalink Structure

#Bonus
wp rewrite structure '/%postname%/'

What Happens to Our Link?


No Big Deal

We could edit the link and keep on being awesome!


But Wait!

What if we have more links to edit?

How about one more link to edit?

wp post create --from-post=1

How about after this?

for i in {1..10}; do !!; done

WP-CLI Search-Replace Cleanup Time

wp search-replace '\/[0-9]{4}\/[0-9]{2}\/[0-9]{2}\/([a-zA-Z0-9-_]+)\/' '/\1' --regex --regex-flags='mi' wp_posts --include-columns=post_content --dry-run

Command All Sites With @alias

Instead of having to SSH into each site, then go to the WordPress directory, then run a WP-CLI command…

Aliases can be registered in your project’s wp-cli.yml file
…or your user’s global ~/.wp-cli/config.yml file:

@prod:
  ssh: [email protected]~/webapps/production
@dev:
  ssh: [email protected]/srv/www/example.dev
@local:
  ssh: vagrant:default
@all:
  - @prod
  - @dev
  - @local                                       

Useful Uses for Using @alias Commands

Security vulnerability in a popular plugin?
All the sites you manage have it installed?
Quickly update the plugin on all sites using WP-CLI’s @alias

wp @all plugin update slug

Heck why not “update all the things”?
This feels like a bit of a cowboy coder move, but when in a pinch…

wp @all core update && wp @all plugin update --all && wp @all theme update --all

One of the million ways to sync databases from a development server to production:

wp @production db export &&
wp @development db export - | wp @production db import - &&
wp @production search-replace "example.dev" "example.com"

Remember when we updated our forgotten user password?
How about this for an even faster way:

wp @alias user update [email protected] --user_pass=C00lP4ssw0rd

Install/Activate Multiple Plugins at Once

You could easily install and activate several, often used, plugins at once.
Do you have a list of plugins you install on every site?

wp @alias plugin install --activate duplicator health-check query-monitor redirection

Scripting Examples (Putting it All Together)


Install WP-CLI and WordPress on Remote Server

wp-init

https://github.com/ecotechie/wp-init


Backing Up WordPress to a Local Directory

wp-backup

https://github.com/ecotechie/wp-backup


Thanks! Questions?

@ecotechie
https://github.com/ecotechie/WordCamp-Santa-Clarita-Valley-2019

Powered by a fork of Daniel Bachhuber’s WP-CLI command: present

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