bash

58 Articles

Windows 10 Goes To Shell

June 10, 2019 by 51 Comments

Windows 10 — the operating system people love to hate or hate to love. Even if you’re a Linux die-hard, it is a fair bet that your workplace uses it and that you have friends and family members that need help forcing you to use Windows at least some times. If you prefer a command line — or even just find a place where you have to use the command line, you might find the classic Windows shell a bit anemic. Some of that’s the shell’s fault, but some of it is the Windows console which is — sort of — the terminal program that runs various Windows text-based programs. If you have the creator update channel on Windows 10, though, there have been some recent improvements to the console and the Linux system that will eventually trickle down to the mainstream users.

What’s New?

So what’s new? According to Microsoft, they’ve improved the call interface to make the following things work correctly (along with “many others”):

  • Core tools: apt, sed, grep, awk, top, tmux, ssh, scp, etc.
  • Shells: Bash, zsh, fish, etc.
  • Dev tools: vim, emacs, nano, git, gdb, etc.
  • Languages & platforms: Node.js & npm, Ruby & Gems, Java & Maven, Python & Pip, C/C++, C# &
  • .NET Core & Nuget, Go, Rust, Haskell, Elixir/Erlang, etc.
  • Systems & Services: sshd, Apache, lighttpd, nginx, MySQL, PostgreSQL

The changes to the console are mostly surrounding escape sequences, colors, and mouse support. The API changes included things like allowing certain non-administrative users to create symlinks. We’ve made X Windows work with Windows (using a third-party X server) and Microsoft acknowledges that it has been done. However, they still don’t support it officially.

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Easy Git Repository Summaries With Web-git-sum

March 25, 2019 by 16 Comments

For those hosting their own git repositories there are a number of solutions for creating convenient web-accessible front ends, but [mitxela] wasn’t quite satisfied with any of them. After trying a number of alternatives and reflecting on his requirements, he realized that all he really needed was a summary page listing the latest commits, and a file tree with a list of branches and tags. To accomplish this, he created web-git-sum. It’s a bash script that runs on git’s post-receive hook and generates only two files: a summary page and an index of the repository. You can see a demo of the output at git.mitxela.com.

[mitxela]’s writeup goes into some detail on how git repositories work, how those repositories are served over HTTP, and covers a few of the different options for providing convenient and accessible web front ends. Not all repositories are alike, and what works well for one may not work or scale well for another.

Intrigued by the idea of a private git server? We covered exactly how to set one up (spoiler: it’s really easy.)

Bash Pipeline Puzzle: Green, Blue, Or Blue Green?

March 10, 2019 by 16 Comments

[Marek Gibney] poses an interesting puzzle. What does the following bash command line print?

( echo red ; echo green 1>&2 ) | echo blue

You’d like to think it prints three lines: red, green, and blue. But would you be surprised to find out that it can sometimes output “blue green” and sometimes just output blue. The first surprise is that it isn’t deterministic. But the second thing that is surprising is the sometimes the entire left-hand part of the line doesn’t do anything. [Chris Siebenmann] did the analysis and explains what’s going on in a recent blog post.

Before you click the link or read further, you might want to see if you can deduce what’s going on. Give up? Here’s a hint: Part of the solution hinges on the fact that echo is built into the shell.

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Linux Fu: The Kitchen Sync

January 10, 2019 by 12 Comments

One of the great things about Linux and similar operating systems is they are configurable. If you don’t like something, there’s a great chance you can change it easily with a few entries in a file somewhere. For example, take bash — a very popular shell by any measure. If you want a different style of command line editing, there’s an option. You want the tab key to match files regardless of case? Another option. Usually, these are set in one of your so-called profile files like .bashrc in your home directory.

As long as you are sitting in front of your single computer working, this is great. You customize your .bashrc and other files to your heart’s content and then you work in an environment that acts the way you want it to. The problem is when you have a lot of computers. Maybe you have a web server, a desktop, a firewall machine, and a few dozen Raspberry Pi computers. How do you keep all the configurations the same? Then once they are the same, how do you keep them up to date?

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Linux Fu: Marker Is A Command Line Menu

October 24, 2018 by 21 Comments

The command line. You either love it or hate it, but if you do anything with a Unix-like system you are going to have to use it eventually. You might find marker — a system billed as a “command palette for the terminal” — a useful program to install. We couldn’t decide if it was like command history on steroids or more of a bookmark system. In a way, it is a little of both.

Your history rolls off eventually and also contains a lot of small commands (although you can use the HISTIGNORE variable to ignore particular commands). With marker, you save specific commands and they stay saved. There are no extra commands nor do the ones you save ever roll off.

Of course, you could just make a shell script or an alias if that’s all there was to it. Marker lets you add a description to the command and then you can search through the commands and the descriptions using a fuzzy incremental search. In addition, you can put placeholders into your command lines that are easily replaced. There are some built-in commands to get you started and the same bookmarks will work in bash and zsh, if you use both.

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Linux Fu: Modernize Your Command Line

August 29, 2018 by 19 Comments

If you use Linux and its associated tools on the desktop or on a Raspberry Pi, or on a server, you probably have used the command line. Some people love it and some people hate it. However, many of us have been using Linux for years and sometimes Unix before that, and we tend to use the same old tried-and-true tools. [Remy Sharp] had a recent post talking about how he had created aliases to replace those old tools with great modern replacements and it is definitely worth a read.

We’ll be honest, when we first saw the post we almost skipped reading it. A lot of Linux tip posts are pretty uninteresting unless you are a total beginner. But [Remy] has a lot of really great tools and how he has them installed including bat, which is like cat but with syntax coloring (see picture above), and fzf — a command line history search on steroids. He even shows how to join fzf and bat to make a very cool file browser from the command line (see below).

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Linux Fu: Scripting For Binary Files

June 29, 2018 by 31 Comments

If you ever need to write a binary file from a traditional language like C, it isn’t all that hard to do. About the worst thing you might have to deal with is attempts to fake line endings across Windows and Linux, but there’s usually a way to turn that off if it is on by default. However, if you are using some type of scripting language, binary file support might be a bit more difficult. One answer is to use a tool like xxd or t2b (text-to-binary) to handle the details. You can find the code for t2b on GitHub including prebuilt binaries for many platforms. You should be able to install xxd from your system repository.

These tools take very different approaches. You might be familiar with tools like od or hexdump for producing readable representations of binary files. The xxd tool can actually do the same thing — although it is not as flexible. What xxd can even reverse itself so that it can rebuild a binary file from a hex dump it creates (something other tools can’t do). The t2b tool takes a much different approach. You issue commands to it that causes it to write an original hex file.

Both of these approaches have some merit. If you are editing a binary file in a scripting language, xxd makes perfect sense. You can convert the file to text, process it, and then roll it back to binary using one program. On the other hand, if you are creating a binary file from scratch, the t2b program has some advantages, too.

I decided to write a few test scripts using bash to show how it all works. These aren’t production scripts so they won’t be as hardened as they could be, but there is no reason they couldn’t be made as robust as you were willing to make them.

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