This post is part 6 of 6 in the series Bash to Zsh

Having used Zsh rather than Bash for over a week it was time to make the move permanent by migrating my shell customisations from ~/.bashrc to ~/.zshrc. Your milage may vary, but I was pleased to find I didn’t need to make any changes, and, that I could get rid of one command from the script because Zsh defaults to a behaviour I had to explicitly opt in to with Bash.

TL;DR: environment variables (including PATH) and aliases work just the same in Zsh as they do in Bash, so if those are the only things you alter in your ~/.bashrc, then you can just copy it over to ~/.zshrc. But, if you alter Bash settings in your ~/.bashrc, you’ll need figure out the equivalent Zsh options and replace the relevant lines with the appropriate Zsh setopt or unsetopt Zsh commands.

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This post is part 1 of 6 in the series Bash to Zsh

During their 2019 World Wide Developers Conference (WWDC 2019) Apple announced that the default command shell for their next OS release (macOS Catalina) from the Bourne Again Shell (Bash) to the Z Shell (Zsh). Not only will Apple be switching the default in Catalina, they will be removing Bash completely in an as-yet unspecified future update. Apple’s advice is clear — make the switch now so you’re ready!

Never being one to try hold back the tide, I dove right in and made the switch within 5 minutes of reading about the announcement. This series will document my experience of making the change.

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This post is part 5 of 6 in the series Bash to Zsh

As I continue my move from Bash to Zsh at Apple’s strong suggestion I continue to bump into little differences that cause me minor problems. Today it was the fact that while Bash treats comments as comments even when they’re entered in an interactive shell, Zsh does not, at least not by default on MacOS.

TL;DRsetopt INTERACTIVE_COMMENTS

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This post is part 4 of 6 in the series Bash to Zsh

At Apple’s advice I’ve switched the login shell from Bash to Zsh on all my Macs. For the most part, what worked in Bash works in Zsh, but sometimes I do still want to get back to Bash to test something or to check something. You might imagine that simply typing bash from a Zsh prompt would get you a Bash shell, and you’d be right, sort of. When you just run the command bash you get a bare shell without the customisations that would have been applied when you opened a new Terminal window with Bash as your default shell. This will be immediately obvious because the prompt will be the basic bash-3.2$ as opposed to the hostname, current folder, and you’re username like you were used to.

The solution is really simple — pass the -l flag to signify that you want your new shell treated like a login shell, and hey presto, you’re back to Bash just like you remembered it 🙂

So, if you switch your Mac to Zsh, you get back to the Bash experience you had before with the following command:

bash -l

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This post is part 3 of 6 in the series Bash to Zsh

At Apple’s recommendation I’ve moved from Bash to Zsh on all my Macs. This has been a mostly smooth transition, but I have run into a handful of little gotchas. This week it was an error when trying to execute a command I’d been using in Bash for years. The error started zsh: no matches found.

The cause of this error is a subtle but important difference in how Bash and Zsh handle file globbing (expansion of the * character) when no files match the specified pattern. By default, Bash happily expands expressions that don’t match anything into an empty list. Zsh’s default behaviour is to raise an error and prevent the command executing.

TL;DRsetopt NULL_GLOB to enable Bash-like behaviour, and unsetopt NULL_GLOB to revert back to the Zsh-like behaviour.

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This post is part 2 of 6 in the series Bash to Zsh

Apple recently announced that it’s moving the MacOS from the Bourne-again Shell (Bash) to the Z Shell (Zsh), and advised developers to make the change now, so they’re ready when they remove Bash altogether in some later version of the OS. Since I’m a big believer in not swimming up-stream, I decided to take their advice and switched to the Z Shell immediately.

The first thing I noticed was that the default prompt Apple provides for Zsh on their OS gives a lot less information than their default for Bash did. This is a sample of their old Bash prompt:

bart-imac2018:Documents bart$

That tells me the machine I’m on (bart-imac2018), the folder I’m in (Documents), and the username the shell is running as (bart), and whether or not I have super-user privileges ($ means no, # means yes). These are all very useful things, particularly when you SSH around a lot and su/sudo to different accounts. Also, IMO showing only the top-level folder rather than the full path gives a nice balance between the prompt getting too big, and not knowing where you are. I’ve never felt an urge to change the Mac’s default Bash prompt.

I can’t say the same about the Mac’s default Z Shell prompt! This is what I get on the same machine with the Z shell:

bart-imac2018%

It only shows the machine name (bart-imac2018) and whether or not I have super-user privileges (% for no, # for yes)!

Thankfully getting back to the old Bash-like prompt is easy — the TL;DR version is that you simply need to add the following line to your ~/.zshrc file:

PROMPT='%m:%1~ %n%# '

If you’d like to understand how exactly that works, and what other choices you have, read on!

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This post is part 37 of 37 in the series Taming the Terminal

Since we covered SSH in parts 29 & 30, Apple have changed how their desktop OS deals with the passphrases protecting SSH identities (key pairs). This provides us a good opportunity to have a look at the SSH Agent in general, and, how things have changed on the Mac in particular.

The good news is that while things have changed on the Mac, with a small amount of effort, you can get back all the convenience and security you had before.

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This post is part 36 of 37 in the series Taming the Terminal

The previous 13 instalments in this series related to networking, but we’re going to change tack completely for this instalment, and look at two un-reltaed, but very useful terminal commands – screen, and cron.

screen is a utility that allows for the creation of persistent virtual terminal sessions that you can disconnect from without terminating, and reconnect and pick up where you left off at a later time. screen is particularly useful when used in conjunction with SSH.

cron on the other hand is a system for automatically executing recurring tasks. It’s extremely flexible, and very useful for things like scheduling backups to run in the middle of the night.

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This post is part 17 of 84 in the series Programming by Stealth

At this stage in the series we have made very good progress towards understanding the core JavaScript language. However, there is still one very important piece missing – objects. We have mentioned them in passing in almost every instalment, and each time, we put them off until later. We finally remedy that in this instalment.

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While it’s very easy to install hsxkpasswd onto your system from CPAN – it’s literally just one command (see below) – it requires administrator access to the machine.

sudo cpan Crypt::HSXKPasswd

This is all well and good if you have administrator access and are sure you want the module installed system-wide. But, what if you don’t have admin access, or, what if you just want to experiment with the module in your own home directory? The answer is perlbrew, a system for running custom versions of Perl inside your home directory. No need for sudo, and what ever you install with perlbrew is entirely contained within your home directory. If you already have perlbrew installed and configured with a version of Perl greater than or equal to 5.16, you can skip to the final step. If not, you’ll need to make your way through all the steps.

Step 1 – Install perlbrew Into Your Home Dir

There are a few different ways of installing perlbrew, but I find the following method the simplest:

curl -L http://install.perlbrew.pl | bash

That should install perlbrew into your home directory, and it should tell you to append some code to the end of your ~/.bash_profile file, which you can do with the following command:

echo 'source ~/perl5/perlbrew/etc/bashrc' >> ~/.bash_profile

Once that’s done, close your Terminal window and open a new one (this is to pick up the new environment variables defined in ~/perl5/perlbrew/etc/bashrc). You’ll know the install has been successful if you can run the perlbrew command:

perlbrew version

Step 2 – Install a Compatible Version of Perl into perlbrew

The joy of perlbrew is that you can have as many versions of Perl installed at any one time as you like, and you can then switch between them with the perlbrew command.

You can install Crypt::HSXKpasswd, and hence the hsxkpasswd terminal command, into any version of Perl greater than or equal to 5.16.

The following command will install Perl 5.16 into perlbrew:

perlbrew install perl-5.16.0

Go off and make yourself a cup of your favourite beverage – this will take a while! 🙂

Once the install finally finishes, you can activate that version of perl (just on your account) with the command:

perlbrew switch perl-5.16.0

It’s important to note that if at any stage you want to disable perlbrew and get back to the default system version of perl, the command to do so is:

perlbrew off

Step 3 – Enable the perlbrew CPAN Client

If you haven’t already done so, enable the perlbrew CPAN client cpanm with the command:

perlbrew install-cpanm

Step 4 – Install Crypt::HSXKPasswd

Once you have perlbrew installed and configured with a compatible version of perl, you can install Crypt::HSXKPasswd with the following simple command:

cpanm Crypt::HSXKPasswd

You’ll know it’s worked if you can run the hsxkpasswd terminal command:

hsxkpasswd --version

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