is

is: an inspector for your environment

Introduction

is is an inspector for your environment. is tries to make it just a little bit easier to run commands which rely on a specific OS or a specific CLI version.

Is the minimum version of this tool available?

is cli version tmux gt 3.2 && echo 🥳 || echo 😢

Is this the target Operating System?

(is os name eq darwin && echo 🍏 ) || (is os name eq linux && echo 🐧) || echo 💣

Check the OS with a Regex

is os name like "da\w{4}" && echo 🍏

Do we have go? Then update go binaries used by vim-go

#!/bin/bash

if is there go; then
    nvim +:GoUpdateBinaries +qa || true
fi

Or, as a one-liner:

is there go && nvim +:GoUpdateBinaries +qa

What's the version of bash?

$ is known cli version bash
5.2.15

Has gofumpt been modified in the last week?

$ is cli age gofumpt lt 7 d
5.2.15

echo the OS name

$ echo "i'm on $(is known os name) for sure"
i'm on darwin for sure

Get some debugging information about the OS

$ is known os name --debug
{
    "name": "darwin",
    "version": "13.4",
    "version-codename": "ventura"
}
darwin

is known os name --debug
{
    "id": "ubuntu",
    "id-like": "debian",
    "name": "linux",
    "pretty-name": "Ubuntu 22.04.2 LTS",
    "version": "22.04",
    "version-codename": "jammy"
}
linux

Can user sudo without a password?

is user sudoer || echo 😭

Exit Codes are Everything

is returns an exit code of 0 on success and non-zero (usually 1) on failure. You can leverage this in shell scripting:

In a script:

#!/bin/bash

if is os name eq darwin; then
  # This is a Mac. Creating karabiner config dir."
  mkdir -p "$HOME/.config/karabiner"
fi

At the command line:

is os name ne darwin && echo "this is not a mac"

Debugging error Codes

In bash and zsh (and possibly other shells), $? contains the value of the last command's exit code.

$ is os name eq x
$ echo $?
1
$ is os name eq darwin
0

Using a Regex

The like and unlike operators accept a regular expression. You may need to quote your regex. For instance:

is os name like darw\w

should be

is os name like "darw\w"

Use the debug flag to see how your regex may have been changed by your shell:

$ is os name like darw\w --debug
comparing regex "darww" with darwin

In this case we can see that the unquoted \w is turned into w by the shell because it was not quoted.

You can also use regexes with no special characters at all:

is os version-codename unlike ventura

Top Level Commands

arch

Checks against the arch which this binary has been compiled for.

is arch eq amd64

is arch like 64

Supported comparisons are:

• lt
• gt
• like
• unlike

Try is known arch to get the value for your installed binary or run this command with the --debug flag.

Theoretical possibilites are:

386
amd64
arm
arm64
loong64
mips
mips64
mips64le
mipsle
ppc64
ppc64le
riscv64
s390x
wasm

however, there are available binaries for only some of these values.

cli

age

Compare against the last modified date of a command's file.

is cli age tmux lt 18 hours

Don't let goimports get more than a week out of date.

is cli age goimports gt 7 days && go install golang.org/x/tools/cmd/goimports@latest

Update shfmt basically daily, but only if go is installed.

if is there go; then
    if is cli age shfmt gt 18 hours; then
        go install mvdan.cc/sh/v3/cmd/shfmt@latest
    fi
else
    echo "Go not found. Not installing shfmt"
fi

Supported comparisons are:

• lt
• gt

Supported units are:

• s
• second
• seconds
• m
• minute
• minutes
• h
• hour
• hours
• d
• day
• days

Note that d|day|days is shorthand for 24 hours. DST offsets are not taken into account here.

The --debug flag can give you some helpful information when troubleshooting date math.

version

Compare versions of available commands. Returns exit code of 0 if condition is true and exit code of 1 if condition is false.

is cli version go gte 1.20.4 || bash upgrade-go.sh

Supported comparisons are:

• lt
• lte
• eq
• gte
• gt
• ne
• like
• unlike

os

Information specific to the current operating system

version

is os version gt 22

is os version like "13.4.\d"

Supported comparisons are:

• lt
• lte
• eq
• gte
• gt
• ne
• like
• unlike

name

Under the hood, this returns the value of runtime.GOOS, a constant which is set at compile time. So, is reports on on the OS name which is the target of build rather than running uname or something like that. This is "good enough" for my purposes. If it's not good enough for yours, we probably need to add more build targets.

Available comparisons are:

• eq
• ne
• like
• unlike

is os name eq darwin

is os name ne linux

is os name like darw

is os name like "dar\w{3}"

is os name unlike "foo\d"

Possible values for name:

darwin
linux

Linux only.

is os pretty-name eq "Ubuntu 22.04.2 LTS"

Available comparisons are:

• eq
• ne
• like
• unlike

Linux only.

is os id eq ubuntu

Available comparisons are:

• eq
• ne
• like
• unlike

is os id-like eq debian

Available comparisons are:

• eq
• ne
• like
• `unlike``

is os version-codename eq jammy

Available comparisons are:

• eq
• ne
• like
• unlike

On Linux, the value for version-codename is taken from /etc/os-release. For Macs, the values are mapped inside this application.

Possible values for Mac:

• ventura
• monterey
• big sur
• catalina
• mojave
• high sierra
• sierra
• el capitan
• yosemite
• mavericks
• mountain lion

there

Returns exit code of 0 if command exists and exit code of 1 if command cannot be found.

is there tmux && echo "we have tmux"

user

sudoer

is user sudoer && sudo apt-get install ripgrep

Returns 1 if the current appears to be able to sudo without being prompted for a password.

This is useful for scripts where you want to install via sudo, but you don't want the script to be interactive. That means you can skip installing things that require sudo and handle them in some other place.

known

Prints known information about a resource to STDOUT. Returns 0 on success and 1 if info cannot be found.

arch

Prints the value of runtime.GOARCH. Note that this is the arch that the binary was compiled for. It's not running uname under the hood.

Theoretical possibilites are:

386
amd64
arm
arm64
loong64
mips
mips64
mips64le
mipsle
ppc64
ppc64le
riscv64
s390x
wasm

however, there are available binaries for only some of these values.

os

Details specific to the current operating system.

Under the hood, this returns the value of runtime.GOOS, a constant which is set at compile time. So, is reports on on the OS name which is the target of build rather than running uname or something like that. This is "good enough" for my purposes. If it's not good enough for yours, we probably need to add more build targets.

$ is known os name
linux

Possible values for name:

darwin
linux

Linux only.

$ is known os pretty-name
Ubuntu 22.04.2 LTS

Linux only.

$ is known os id
ubuntu

Linux only.

$ is known os id-like
debian

$ is known os version
22.04

$ is known os version-codename
jammy

cli version

$ is known cli version tmux
3.3a

--debug

Print some debugging information to STDOUT.

$ is os name eq darwins --debug
Comparison failed: darwin eq darwins

--help

Top level command help.

Usage: is <command>

Flags:
  -h, --help       Show context-sensitive help.
      --debug      turn on debugging statements
      --version    Print version to screen

Commands:
  os <attribute> <op> <val>
    Check OS attributes. e.g. "is os name eq darwin"

  cli version <name> <op> <val>
    Check version of command. e.g. "is cli version tmux gte 3"

  cli age <name> <op> <val> <unit>
    Check last modified time of cli (2h, 4d). e.g. "is cli age tmux gt 1 d"

  known os <attribute>
    Print without check. e.g. "is known os name"

  known cli <attribute> <name>
    Print without check. e.g. "is known cli version git"

  there <name>
    Check if command exists. e.g. "is there git"

  user [<sudoer>]
    Info about current user. e.g. "is user sudoer"

Run "is <command> --help" for more information on a command.

subcommand --help

Usage: is os <attribute> <op> <val>

Check OS attributes. e.g. "is os name eq darwin"

Arguments:
  <attribute>    [arch|id|id-like|pretty-name|name|version|version-codename]
  <op>           [eq|ne|gt|gte|lt|lte]
  <val>

Flags:
  -h, --help       Show context-sensitive help.
      --debug      turn on debugging statements
      --version    Print version to screen

--version

Print current version of is

is --version

Installation

• Download a release
• go install
  • go install github.com/oalders/is@latest
  • go install github.com/oalders/is@v0.1.3
• Use ubi

#!/usr/bin/env bash

set -eux

INSTALL_DIR="$HOME/local/bin"

if [ ! "$(command -v ubi)" ]; then
    curl --silent --location \
        https://raw.githubusercontent.com/houseabsolute/ubi/master/bootstrap/bootstrap-ubi.sh |
        TARGET=$INSTALL_DIR sh
fi

ubi --project oalders/is --in "$INSTALL_DIR"

Bonus: Easier Version Parsing of Available Tools

Forget about the remembering the different version incantations of command line tools. Don't make up regexes to extract the actual version number.

Go (version)

$ go version
go version go1.20.4 darwin/amd64

$ is known cli version go
1.20.4

Perl (--version)

$ perl --version

This is perl 5, version 36, subversion 1 (v5.36.1) built for darwin-2level

Copyright 1987-2023, Larry Wall

Perl may be copied only under the terms of either the Artistic License or the
GNU General Public License, which may be found in the Perl 5 source kit.

Complete documentation for Perl, including FAQ lists, should be found on
this system using "man perl" or "perldoc perl".  If you have access to the
Internet, point your browser at https://www.perl.org/, the Perl Home Page.

$ is known cli version perl
v5.36.1

tmux (-V)

$ tmux -V
tmux 3.3a

$ is known cli version tmux
3.3a