x-is

name	x-is
description	Value validation and environment detection tool for Shell scripts. Validates input types (integers, floats, IPs), compares file ages, detects runtime environments (TTY, WSL, Termux, Cygwin). Supports batch checking with exit code 0 success / 1 failure. Trigger when user needs to validate input types, detect terminal environment, check file freshness, verify variable states, or perform environment suitability checks (suitable_pkg/suitable_advise). Keywords: validate, check, verify, is, integer, float, positive, negative, range, IP address, file age, interactive, WSL, Termux, environment detection, unset variable, batch check.
license	MIT
compatibility	POSIX Shell (sh/bash/zsh/dash/ash)
metadata	{"author":"X-CMD","version":"1.0.0","category":"core","tags":["shell","cli","tools","validation","type-check","environment-detection"],"repository":"https://github.com/x-cmd/skill","display_name":"Value & Environment Validator"}

x is - Value & Environment Validation

x is is x-cmd's value validation tool for checking if values or environment states meet specific criteria. Supports batch checking multiple values, ideal for robust Shell scripting.

Prerequisites

1. Load x-cmd before use:

   . ~/.x-cmd.root/X
   

Core Usage

• Type Check: x is int 42 100 -5 / x is float 3.14
• Range Check: x is minmax 1 100 50 75
• Compare: x is eq "a" "a" / x is within "ok" pending success
• IP Check: x is ip 192.168.1.1
• File Age: x is newest target src/*.c / x is oldest cache.txt /tmp/*.tmp
• Variable Check: x is unset VAR1 VAR2
• Environment Detection: x is interactive / x is wsl / x is termux

Subcommands

Type

Command	Description
int	Integer check, batch supported
float	Float check (must contain decimal point)
positive	Positive integer (≥0)
negative	Negative integer (<0)
minmax	Range check [MIN,MAX]

Compare

Command	Description
eq	Multiple values equal
within	First value in candidate list
in	Colon-separated list member check
in-	Dash-separated list
in_	Underscore-separated list
in/	Slash-separated list
in|	Pipe-separated list

Network

Command	Description
ip	IPv4 address check

File

Command	Description
newest	File newer than others (glob supported)
oldest	File older than others (glob supported)

Variable

Command	Description
unset	Variable is unset

Environment

Command	Description
interactive	Interactive session
interactive_tty	stdin is interactive TTY
interactiveshell	Shell is interactive
repl	REPL mode
stdout2tty	stdout outputs to TTY
wsl	WSL environment
cygwin	Cygwin environment
msys	MSYS/MinGW environment
gitbash	Git Bash environment
termux	Termux environment
ish	iSH environment

Suitability

Command	Description
suitable_pkg	Suitable for package installation
suitable_advise_env	Suitable for advise feature
suitable_advise_repl	Suitable for advise REPL

Practical Examples

Batch Type Validation

x is int 1 2 3 4 5 && echo "All integers"
x is float 3.14 -2.5 .5 && echo "All floats"

Environment Conditional Branch

x is interactive && echo "Interactive session" || echo "Script mode"
x is wsl && echo "WSL environment" || echo "Not WSL"
x is termux && echo "Termux environment"

File Status Check

x is newest build.tar.gz src/*.c lib/*.h || echo "Rebuild needed"

Variable Cleanup Verification

x is unset TEMP_VAR1 TEMP_VAR2 && echo "Temp variables cleaned"

Script Pre-flight Check

x is suitable_pkg || { echo "Environment not suitable"; exit 1; }

Design Principles

• Batch First: Check multiple values at once, all must pass
• Exit Code Semantics: 0 = success, 1 = failure, perfect for &&/|| chains
• Silent: Validation tool outputs nothing, only exit code indicates result

Get Help

x is --help