shell - Julio Merino (jmmv.dev)

Useless use of GNU

The GNU project is the source of the Unix userland utilities used on most Linux distributions. Its compatibility with standards and other Unix systems, or lack thereof, directly impacts the overall portability of any piece of software developed from GNU/Linux installations. Unfortunately, the GNU userland does not closely adhere to standards, and its widespread usage causes little incompatibilities to creep into any software created on GNU/Linux systems. Read on for why this is a problem and the pitfalls you will encounter.

August 25, 2021 · Tags: opinion, programming, shell, unix
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test, [, and [[

A little essay on the amusement or horror that may bring to learn that both test and [ are binaries on your typical Unix system, and that [[ is subject to completely different rules.

March 25, 2020 · Tags: shell
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The /bin/bash baggage of macOS

As you may know, macOS ships with an ancient version of the Bash shell interpreter, 3.2.57. Let’s see why that is and why this is a problem.

November 20, 2019 · Tags: macos, shell
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Shell readability: local

As most programming languages with support for functions, the shell offers locally-scoped variables. Unfortunately, local variables are not the default. You must explicitly declare variables as local and you should be very strict about doing this to prevent subtle but hard-to-diagnose bugs. That’s it! What else is there to say about this trivial keyword? As it turns out, more than you might think.

March 13, 2018 · Tags: readability, shell
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Shell readability: strict mode

Some programming languages have a feature known as strict mode: a setting that makes the language interpreter disallow certain obviously-broken code that would otherwise work. The simplest examples are JavaScript and Perl but, as it turns out, the shell also has something akin to this feature. The “strict mode” name, however, is unofficial, so you won’t find many references to it online. You can enable the shell’s strict mode by doing one of the following:

March 9, 2018 · Tags: featured, readability, shell
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Shell readability: function parameters

The shell supports defining functions, which, as we learned in the previous post, you should embrace and use. Unfortunately, they are fairly primitive and their use can, paradoxically, introduce other readability problems. One specific problem is that function parameters are numbered, not named, so the risk of cryptic code is high. Let’s see why this is a problem.

March 2, 2018 · Tags: readability, shell, shtk
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Shell readability: main

Our team develops Bazel, a Java-based tool. We do have, however, a significant amount of shell scripting. The percentage is small at only 3.6% of our codebase… but given the size of our project, that’s about 130,000 lines—a lot, really. Pretty much nobody likes writing these integration tests in shell. Leaving aside that our infrastructure is clunky, the real problem is that the team at large is not familiar with writing shell per se.

February 26, 2018 · Tags: readability, shell, shtk
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Introducing shtk

Have you ever wanted to have a collection of ready-to-use modules for shell scripts? I have, particularly because I keep reimplementing the same functions over and over and over and over again whenever I write non-trivial shell scripts, and I'm tired of doing so. That's why I have just abstracted all the common code in the aforementioned tools and put it into a new package called the "Shell Toolkit", or shtk for short.

August 15, 2012 · Tags: announce, netbsd, shell, shtk, sysbuild, sysupgrade
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Posts: shell