: Is zsh posix compliant x, GPL v2; newer bash use GPLv3+; zsh is using MIT like license. Bash POSIX Mode (Bash Reference Manual)6. A number of Unix services, tools, and functions are part of the standard, ranging from the basic system calls and C library functions to common applications and tools to system administration and management. It‘s a small but smart improvement. z/OS UNIX supports a set of standards called the portable operating system interface (POSIX). Jul 13, 2019 · Zsh can run most Bourne, POSIX or ksh88 scripts if you put it in the right emulation mode (emulate sh or emulate ksh). Note: When writing a bash or zsh script, use [[ instead of POSIX [. In any case, it's not and never was intended to be a POSIX compliant interpreter for the sh language (at least not in its Please note that, whilst reasonable efforts are taken to address incompatibilities when they arise, zsh does not guarantee complete emulation of other shells, nor POSIX compliance. Do you know any resource to learn how to do things entirely in POSIX compliant code? I know I can set my shell to bash for the specific scripts but that's not what i'm after. See z/OS UNIX System Services User's Guide for more information about POSIX compliance. /bin/sh on the other hand is a standin for any POSIX shell, and only POSIX scripts should use it. You can replicate Fish’s features in Zsh with Sep 11, 2021 · zsh is not a POSIX shell, it was written before the POSIX specification of sh was released, took features and syntax from ksh, csh, tcsh, rc and added many of its own. are POSIX compliant Uhm, sort'a kind'a. Jun 8, 2019 · Speaking as someone who's used both and landed on bash -- the only thing that made me really, deeply unhappy with zsh was its decision to break POSIX compliance when the standard canonicalizes admittedly-bad design decisions in ways that made it easy to get sloppy about correctness when trying to write scripts that needed to be compatible with other, strictly-POSIX-superset shells 6 It is the POSIX standard that defines the $(command) form of command substitution. It looks like a situation where everyone involved was already familiar with the intended behavior (as per Chet Ramey [1]) and baked their assumptions into the drafted text, leaving it less explicit than it should have been. Description zsh is a UNIX command interpreter (shell) that is used as an interactive login shell and as a shell script command processor. As an example of why fish is not POSIX-compliant, it does not understand the var=value syntax for setting variables. Which fish still can't run, so you're right, but the emphasis is wrong when you say "cannot run posix sh or May 12, 2025 · Non-POSIX-compliant: Unlike Bash and Zsh, Fish is not POSIX-compliant, which means that scripts written for Bash or other POSIX-compliant shells may not run correctly in Fish without modification. May 12, 2025 · Disadvantages of Fish: Non-POSIX-compliant: Unlike Bash and Zsh, Fish is not POSIX-compliant, which means that scripts written for Bash or other POSIX-compliant shells may not run correctly in Fish without modification. The only real-world sensible recommendation is test your macOS ships with bash 3. To do that, you may either download May 15, 2020 · Fish vs. In most cases, POSIX-compliance is a fool's errand since there are significant differences between implementations of even the same shell (e. It has command-line editing, built-in spelling correction, programmable command completion, shell functions (with autoloading), a history mechanism, and a host of other features. shell bash zsh library posix dash shell-extension shellcode ksh mksh sh posix-sh shell-scripting ash ksh93 yash posix-compatible posix-compliant Updated on Nov 3, 2024 Shell Feb 6, 2024 · Being POSIX-compliant may be essential to some, but it is not the be-all-and-end-all. shells like bash, zsh, etc. nvm works on any POSIX-compliant shell (sh, dash, ksh, zsh, bash), in particular on these platforms: unix, macOS, and windows WSL. ) to get a shell that will work as a POSIX shell. Unfortunately, making a shell script 'POSIX-compliant' is usually easier than making it run on any real-world shell. Nov 25, 2023 · Some comments here seem unaware that all Unixes must have a Bourne-compatible shell (/bin/sh) in order to meet the requirements of POSIX and the Unix trademark, and there is a longstanding tradition that scripts intended for sharing/distribution are expected to only use Bourne shell syntax so they can run on any Unix or Unix-like OS without modification. To reiterate my question, why should any scriptwriter spend time concerning themselves with POSIX compliance? Oct 28, 2024 · Among the various shells available, Zsh (Z Shell) stands out as a feature-rich and customizable alternative to the more traditional Bash shell. js, designed to be installed per-user, and invoked per-shell. In 2020, Kali Linux (Debian-derived, primarily for digital forensics and penetration testing) adopted Zsh as the default shell. ZSH Follows POSIX Standards The POSIX standard defines how Unix-style shells should operate. Fish and Nushell are not POSIX compliant, which means you’ll run into many instances where behavior deviates from standard expected shell behavior. I’d advise for Zsh. Discover which is better for scripting, performance, customization, and productivity in your terminal workflow. For me this means its support for read -r is also an accident or a deliberate courtesy. What does it mean? A shell that mets the specification. " So, I think the goal of POSIX is portability, but, at least in my experience, my scripts would be more portable if they worked in bash and ignored POSIX than the other way around. Installing and Updating Install & Update Script To install or update nvm, you should run the install script. Most shells in use today are POSIX compliant and support this preferred form over the archaic backtick notation. Bash completion support (by internally invoking the genuine Bash). Also I can't stand people complaining about bloat when talking about such things. The POSIX Shell and Utilities standard was originally developed Oct 26, 2017 · Can you please explain why? Or maybe point to a relevant web-resource about POSIX-compliants shells? Or POSIX manual relevant section that describes the shell behavior in the case described in question? A command-line shell that focuses on productivity and swiftness featuring: A POSIX compliant interactive shell with some Bash extensions. sh) is the "POSIX shell"? I don't think it is. ) on various platforms The NFS supports file access to the z/OS UNIX file system. Thanks POSIX compliant shell. Apr 1, 2023 · On Fri, Mar 31, 2023, at 4:16 PM, Felipe Contreras wrote: > I think everyone can agree POSIX is not clear about this. IMO, Nushell shines in Docker containers where you want to pipeline CLI tool outputs to one another, and Fish’s has some good features at cost of too many syntax changes. Limited Compatibility: Because Fish is a newer shell, it has a smaller community and fewer resources than Bash and Zsh. Zsh, while mostly compatible with Bash, prioritizes features and user experience over strict POSIX compliance. Its syntax is for a large part Korn-like, but that doesn't mean it's fully compatible with the Korn shell. Its key feature is a focus on a high level of customization by the user, which has led to an active community of developers creating extensions for zsh, including custom, more informative prompt status lines, often integrating with system services. It offers advanced capabilities such as advanced tab completion, powerful scripting features, and extensive customization options through its robust configuration system. Mar 30, 2023 · On Thu, Mar 30, 2023 at 6:05 AM Lawrence Velázquez <larryv@xxxxxxx> wrote: > > On Mar 30, 2023, at 7:13 AM, Felipe Contreras <felipe. Much of the trouble with POSIX-compliant shells is BECAUSE of POSIX, since it captures the poor behavior and syntax that existed. /sh $ . js versions (zsh extras) - LnxFCA/nvm-zsh Yes, they aren't POSIX compliant but are the most common scripting languages and zsh and bash have good compatibility as far as I know, but Fish is almost completely different. When Bash, mksh AUR and zsh are invoked with the sh name, they automatically become more POSIX compliant. Performance Performance is the price you have to pay for flexibility, and for a while it felt that the customizability and features of ZSH were worth it. b. However, there are many other shells available for use, including, but not limited to: Z shell, TC shell, RC shell and the Bourne Again shell. Written in Rust 🦀. > > We ignore Apr 4, 2019 · Make PowerShell not only POSIX compliant, but also ZSH & BASH compatible. Portable However, even so, all the above does not ensure "portability". Variable conditionals Use these to check if a variable is Since it's rust based and relatively new you'll have to compile it yourself or get the premade binaries. The command substitution section (2. Good luck. X-seq: zsh-workers 22180 From: Vincent Lefevre <vincent@xxxxxxxxxx> To: zsh-workers@xxxxxxxxxx Subject: zsh: jobs -p is not POSIX-compliant Date: Tue, 31 Jan 2006 13:25:20 +0100 Mail-followup-to: Vincent Lefevre <vincent@xxxxxxxxxx>, zsh-workers@xxxxxxxxxx Mailing-list: contact zsh-workers-help@xxxxxxxxxx; run by ezmlm Nov 26, 2024 · On the other hand, Bash excels in simplicity with POSIX compliance and in scripting with strong automation and cross-platform capabilities. POSIX, which stands for Portable Operating System Interface, is a set of standards that ensures compatibility and portability across different operating systems. Zsh offers robust autocomplete with intuitive multicolumn dropdown menus not found in the other shells. Zsh is a POSIX-compliant shell that has been around for a long time and zsh is a POSIX-compatible shell, and a popular alternative to the Bourne shell (sh) and bash. However, after some reconsideration, I decided to port my config to the Fish shell, and this is why. when installing zsh starting from busybox. Jan 21, 2024 · internationalization and localization, and multi-byte character encoding. You will do well to utilize the full features of your shell when writing scripts. Nonetheless, I switched from fish to zsh a few months ago, because of POSIX compliance. 1 What is POSIX? ¶ POSIX is the name for a family of standards based on Unix. Zsh has most features of bash, but in many cases with a different syntax. Thus, Zsh is the ideal choice when advanced customization and a modern user experience are desired, while Bash serves best for standardized scripting and in terms of being highly reliable. The shell that runs the scripts is the one indicated in the first line, the shell bash zsh library posix dash shell-extension shellcode ksh mksh sh posix-sh shell-scripting ash ksh93 yash posix-compatible posix-compliant Updated Nov 3, 2024 Shell ko1nksm / getoptions Sponsor Star 416 Code Issues Pull requests Discussions About nvm is a version manager for node. From the zsh docs about zsh on page 1: It does not provide compatibility with POSIX or other shells in its default operating mode. Hi, I love zsh and also love scripting. Mar 18, 2024 · Learn about different POSIX-compliant shells and how to use the ShellCheck utility to check for the compliance of scripts. Each occurrence in the input of an IFS character that is not > IFS white space, along with any adjacent IFS white space, shall > delimit a field, as described previously. ZSH aims for POSIX compliance, while Fish ignores these It can run almost all Bourne scripts and POSIX compliant scripts, and operating systems often use bash as /bin/sh. 6. bash scripts will work in zsh just fine, I didn't know if zsh is POSIX compatible unless you exclude bash constructs. Feb 11, 2018 · The biggest risks in using a non-compliant shell are that you might get in habits that result in buggy code when writing code that well be executed with a compliant shell (this is particular risk for zsh, as it looks enough like a POSIX shell that habits can translate easily and result in only subtle bugs that aren't immediately caught), and you're liable to annoy any coworkers who need to Mar 29, 2025 · Bash vs Zsh vs Fish: Learn the key differences between the top Linux shells in 2025. Most contemporary versions of UNIX provide three shells--the Bourne and/or POSIX shell, the C shell, and the Korn shell--as standard equipment. Small critique - bash scripts should always be prefixed with /bin/bash (or /bin/env bash) and it makes no sense to worry about whether a seperate shell will be compatible with a bash script. Cicada is trying to support most common cases that Bash supports, except the Bash scripting language. This article dives into the differences between Bash and Zsh, comparing their features, scripting capabilities, performance, and customization options to help users choose the right shell for their needs in 2025. The shell interpreters the following flags to determine where the shell will Node Version Manager - POSIX-compliant bash script to manage multiple active node. Dec 16, 2024 · Autocomplete and Suggestions Fish has the most automatic, intuitive suggestions based on history and current working directory. If you are going to learn non-POSIX things they should be for the default Linux shell, not some broken upstart that can’t decide what it Sep 5, 2021 · Additionally in general Zsh does not try to be POSIX-compliant in the first place. May 21, 2025 · Bash strictly adheres to POSIX standards, which ensures broad compatibility across Unix-like systems. Oct 1, 2024 · ZSH is also POSIX-compliant, which was very important to me for some reason. Zsh appears not to be POSIX compliant. May 20, 2024 · Exploring Zsh and POSIX Compliance As a user who regularly interacts with the command line, I’ve found Zsh to be a powerful and feature-rich shell. g. Simple as that! About nvm is a version manager for node. As for POSIX compliance, this is from their FAQ: Compare to Other Shells Bash is where most people come from and what they are familiar with. archlinux. Many configurations with large sets of sensible Feb 21, 2021 · Shells like Bash or Zsh are advanced and user-friendly, and include features beyond what a simpler POSIX-compliant shell might offer. May 25, 2021 · So what would a shell need to be "SH compliant" or "POSIX-like compliant shell"? Aside from reading commands to be executed and storing a few variables, there is not a whole lot a shell really does so I would assume it's only syntacticaly. 3) of the Shell Language document describes this: Because what you like about Fish can be done optionally in Bash or ZSH with better posix compliance and no need to learn or swap syntax. Sometimes we use "SUS" to refer to the full standard, and "POSIX" to refer to the base standard and possibly the non-Unix-centric option groups. Scripting Languages Fish utilizes a unique scripting format that deviates from POSIX standards. Being able to pipe structured data makes it possible, in principle, to solve many problems directly from the command line that previously required writing custom programs. Bash — Bash extends the Bourne shell with command-line history and completion, indexed and associative arrays, integer arithmetic, process substitution, here strings, regular expression matching and brace expansion. With z/OS UNIX, the NFS performs the following functions. cat somefile Failure to Meet POSIX Compliance Zsh is not POSIX compliant as people claim. org I mean, yes, scripts should be written in POSIX compliant sh but the rest I do use zsh as an interactive shell exclusively because it does support plugins which I don't want to write myself btw and it can and does look like a shell from 2022 not 1970. ksh, bash, and zsh are all considered Apr 11, 2025 · Learn the key differences between Zsh and Bash—two powerful Unix shells. Tab completions and syntax highlighting. Because bash has many extensions it is not a good shell to use for determining POSIX compliance. In following aspects, cicada wants to do a Jul 12, 2024 · Describe the bug Installation instructions are not POSIX compliant, which could be useful e. Discover which shell suits your workflow—scripting, customization, or beginner-friendly use. Initially, I liked the idea of having a cleaner, streamlined syntax and thought I would simply learn everything on-the-fly. (which means POSIX is a subset of SUS) Only the compliant operating systems can use the "UNIX" trademark. Choosing the right shell to use is an important decision because you will spend considerable time and effort Aug 22, 2024 · Understanding the Differences Between Unix Shells: bash, csh, dash, ksh, shh, tcsh, and zsh Unix-like operating systems offer various command-line shells, each with unique features and About nvm is a version manager for node. See full list on wiki. Use cat instead. The shell you use interactively is irrelevant for any script you have. Notably by invoking it with a basename of sh or -sh, or by use of the POSIXLYCORRECT environment variable. , Bash, etc. Bash and Why You Should Switch to Fish There are two kinds of *nix users: the cautious and the adventurous Here’s a fact, most developers love Unix and Unix-like (Linux-based) … Mar 19, 2025 · Scripting c apabilities Bash — Due to its POSIX compliance and speed, Bash is better suited for scripting and automation Zsh — Offers more customization for an intuitive scripting experience but lacks universal acceptance due to its POSIX limitation Auto- c ompletion and c ommand h istory Bash — Uses a simple tab and interface, making it the go-to for users who are more focused on May 2, 2016 · The book says : When in POSIX-compatible mode, bash will emulate sh. It's 2022. In this article, we’ll delve into the features that make Zsh a favorite among developers and system administrators alike, how to get started with it, and tips for enhancing your command line experience. /sh There are plenty of alternatives (dash, posh, lksh, bash, zsh, etc. What does this mean? What is meant by emulation in simple layman terms? Jan 22, 2013 · defined in a script (file), but not loaded into a running process yet? OR defined in a running process script, the code possibly being loaded from an external file that was sourced or in-line per the program? Are you sure Bourne shell (. Jan 21, 2024 · Are you sure about that, zsh shell is backward compatible with bash, e. Mar 28, 2022 · Instead, Linux is seen as being mostly POSIX-compliant. Builtin zero configration features. I don't want to start any kind of negative feedback loop here, but I'm thinking about a way for folks like me to give Power A POSIX-compliant shell is one that does everything demanded by the specification of the sh program in POSIX. contreras@xxxxxxxxx> wrote: > > However, this is what POSIX says: > > 3. For the curious, a bug report has been May 15, 2023 · Arithmetic Parameter expansion Replacement Length Default Value Escape sequences Text Colors Text Attributes Internal and environment variables References Conditional expressions For use in [ ] if [ ]; then and test. Does one need to prefer shells that are POSIX compliant? Depends Dec 2, 2016 · $ ln -s /bin/bash . Experienced developers may favor Bash or Zsh to leverage more common Single UNIX Specification POSIX standards form the core of the Single UNIX Specification. Use of that broken redirection suggestion is proof of that. May 21, 2025 · Nushell is a modern shell that supports piping rich, structured data, addressing a significant pain point with how pipes work in POSIX-compliant shells. Bash can be made to behave in a (more or less) POSIX compliant manner. May 13, 2024 · Is Zsh Posix Compliant? As a developer who loves to explore different shells, I have always been curious about the POSIX compliance of Zsh. The floating point math is another. I do agree. It doesn't support all features of bash or ksh93. 11. Zsh vs. Dec 27, 2023 · With ZSH, you end up with a cluttered history full of minor variations of the same command: ls -lh ls -lh /home/ ls -lah ls /home/docs Fish condenses all those ls variants into a single history entry. I'm having trouble managing those two things because it seems all the learning resources for shell scripting are based heavily on Bash.

Is zsh posix compliant. Builtin zero configration features.