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

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

#!/bin/bash

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

Or, as a one-liner:

is there go && nvim +:GoUpdateBinaries +qa

$ is known cli version bash
5.2.15

$ is cli age gofumpt lt 7 d
5.2.15

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

$ 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

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"

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

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Don't let goimports get more than a week out of date.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

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

Information specific to the current operating system

is os version gt 22

Supported comparisons are:

• lt
• lte
• eq
• gte
• gt
• ne

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

is os name eq darwin

is os name ne linux

Possible values for name:

darwin
linux

Linux only.

is os pretty-name eq "Ubuntu 22.04.2 LTS"

Available comparisons are:

• eq
• ne

Linux only.

is os id eq ubuntu

Available comparisons are:

• eq
• ne

is os id-like eq debian

Available comparisons are:

• eq
• ne

is os version-codename eq jammy

Available comparisons are:

• eq
• ne

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

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"

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.

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

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

$ is known cli version tmux
3.3a

Print some debugging information to STDOUT.

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

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.

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

Print current version of is

is --version

• Download a release
• go install
  • go install github.com/oalders/is@latest
  • go install github.com/oalders/is@v0.1.1
• 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"

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 go1.20.4 darwin/amd64

$ is known cli version go
1.20.4
$ is known os name
darwin

$ 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 3.3a

$ is known cli version tmux
3.3a