How do I install the Cross Platform Scripting skill?

Run npx skillmds@latest add sergeyitaly/cross-platform-scripting in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Cross Platform Scripting safe to use?

This skill has not completed SkillMD's automated safety review yet. Capability flags: docs only. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Cross Platform Scripting?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Cross Platform Scripting free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Cross Platform Scripting?

sergeyitaly (@sergeyitaly) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Cross Platform Scripting by sergeyitaly

Name: Cross Platform Scripting
Rating: 4.666666666666667 (3 reviews)
Author: sergeyitaly

Cross Platform Scripting

Detect the host OS (Windows/macOS/Linux) and PowerShell version (5.1 Desktop vs 7+ Core) before writing or editing scripts, and write/adapt .ps1, .sh, and .cmd scripts to match what's actually available — avoiding PS7-only syntax on PS5.1, GNU-only flags on macOS/BSD tools, and Windows-only assumptions on POSIX shells. Use before writing a new script, when a script fails with a syntax/parameter error that looks version- or OS-specific, or when asked to make a script cross-platform.

sergeyitaly Updated Sep 22, 2026

File contents

Cross-Platform Scripting

Detect the actual runtime before assuming what syntax/tools are available — don't write PS7 syntax for a PS5.1 host, or GNU sed flags for macOS.

1. Detect the OS

PowerShell 6+/7+: $IsWindows, $IsMacOS, $IsLinux (booleans).
PowerShell 5.1: these variables don't exist — PS5.1 only runs on Windows, so its mere presence ($PSVersionTable.PSEdition -eq 'Desktop') implies Windows.
From a POSIX shell: uname -s → Linux, Darwin (macOS), or MINGW*/MSYS*/CYGWIN* (Git Bash / WSL-adjacent on Windows).
If a project ships parallel scripts (setup.ps1 + setup.sh, or *.cmd + *.ps1), that's a signal contributors use multiple OSes — keep both in sync when changing behavior.

2. Detect PowerShell version before writing/editing .ps1

$PSVersionTable.PSVersion          # e.g. 5.1.19041.x or 7.4.x
$PSVersionTable.PSEdition           # "Desktop" (5.1) or "Core" (7+)

Check the project's existing scripts for a stated minimum (a comment like "PS5-compatible" or #Requires -Version 7.0) — match that, don't assume the latest syntax is fine.

3. PS7+-only syntax to avoid on PS5.1

Feature	PS7+	PS5.1-safe equivalent
Pipeline chain operators	`cmd1 && cmd2`, `cmd1 \|\| cmd2`	`cmd1; if ($?) { cmd2 }`
Ternary	`$x ? $a : $b`	`if ($x) { $a } else { $b }`
Null-coalescing	`$a ?? $b`, `$a ??= $b`	`if ($null -eq $a) { $b } else { $a }`
`ForEach-Object -Parallel`	available	sequential `foreach`/`ForEach-Object`, or `Start-Job`/runspaces
`Get-Error`	available	inspect `$Error[0]` / `$_.Exception`
`&&`/`\|\|` for native exe stderr capture	works as expected	redirecting a native command's stderr inside PS5.1 wraps it as a `NativeCommandError` and can flip `$?` to `$false` even on exit 0 — avoid `2>&1` on native exes; capture stdout/stderr separately if needed

When a script must support both, default to PS5.1-safe syntax and add #Requires -Version 7.0 only if a PS7+-only feature is genuinely needed — then document that requirement at the top of the script and in any README that lists prerequisites.

4. Cross-OS path and tool differences

Use Join-Path (PowerShell) or path-library functions instead of hardcoded \ or / separators.
sed -i differs: GNU sed -i 's/x/y/' file vs BSD/macOS sed -i '' 's/x/y/' file (macOS requires the empty extension argument). Prefer perl -i -pe or a small Python/Node one-liner when a script must run on both.
Line endings: scripts checked out on Windows may get CRLF; .sh scripts with CRLF line endings fail with bad interpreter on Linux/macOS — check .gitattributes for * text=auto or explicit eol=lf rules on shell scripts.
Test-Path/New-Item -ItemType Directory -Force (PowerShell) vs [ -d "$dir" ]/mkdir -p (POSIX) — don't mix syntaxes within one script.

5. When generating a new script

Detect (or ask) which environment(s) it must run on.
If the project already has a script for the same task in another shell (.ps1 next to .sh), match its behavior and keep both updated.
Default to the most restrictive compatible syntax (PS5.1 / POSIX sh) unless the task genuinely needs a newer feature — then state the requirement explicitly (#Requires -Version 7.0, #!/usr/bin/env bash with a documented bash-version minimum).
Test the script (or at least syntax-check it: pwsh -NoProfile -Command "& { . ./script.ps1 -WhatIf }" style dry runs, or bash -n script.sh) before declaring it done.

---name: cross-platform-scriptingdescription: Detect the host OS (Windows/macOS/Linux) and PowerShell version (5.1 Desktop vs 7+ Core) before writing or editing scripts, and write/adapt .ps1, .sh, and .cmd scripts to match what's actually available — avoiding PS7-only syntax on PS5.1, GNU-only flags on macOS/BSD tools, and Windows-only assumptions on POSIX shells. Use before writing a new script, when a script fails with a syntax/parameter error that looks version- or OS-specific, or when asked to make a script cross-platform.---# Cross-Platform ScriptingDetect the actual runtime before assuming what syntax/tools are available —don't write PS7 syntax for a PS5.1 host, or GNU `sed` flags for macOS.## 1. Detect the OS- **PowerShell 6+/7+**: `$IsWindows`, `$IsMacOS`, `$IsLinux` (booleans).- **PowerShell 5.1**: these variables don't exist — PS5.1 only runs on Windows, so its mere presence (`$PSVersionTable.PSEdition -eq 'Desktop'`) implies Windows.- **From a POSIX shell**: `uname -s` → `Linux`, `Darwin` (macOS), or `MINGW*`/`MSYS*`/`CYGWIN*` (Git Bash / WSL-adjacent on Windows).- If a project ships parallel scripts (`setup.ps1` + `setup.sh`, or `*.cmd` + `*.ps1`), that's a signal contributors use multiple OSes — keep both in sync when changing behavior.## 2. Detect PowerShell version before writing/editing .ps1```powershell$PSVersionTable.PSVersion # e.g. 5.1.19041.x or 7.4.x$PSVersionTable.PSEdition # "Desktop" (5.1) or "Core" (7+)```Check the project's existing scripts for a stated minimum (a comment like"PS5-compatible" or `#Requires -Version 7.0`) — match that, don't assumethe latest syntax is fine.## 3. PS7+-only syntax to avoid on PS5.1| Feature | PS7+ | PS5.1-safe equivalent ||---|---|---|| Pipeline chain operators | `cmd1 && cmd2`, `cmd1 \|\| cmd2` | `cmd1; if ($?) { cmd2 }` || Ternary | `$x ? $a : $b` | `if ($x) { $a } else { $b }` || Null-coalescing | `$a ?? $b`, `$a ??= $b` | `if ($null -eq $a) { $b } else { $a }` || `ForEach-Object -Parallel` | available | sequential `foreach`/`ForEach-Object`, or `Start-Job`/runspaces || `Get-Error` | available | inspect `$Error[0]` / `$_.Exception` || `&&`/`\|\|` for native exe stderr capture | works as expected | redirecting a native command's stderr inside PS5.1 wraps it as a `NativeCommandError` and can flip `$?` to `$false` even on exit 0 — avoid `2>&1` on native exes; capture stdout/stderr separately if needed |When a script must support both, default to **PS5.1-safe syntax** and add`#Requires -Version 7.0` only if a PS7+-only feature is genuinely needed —then document that requirement at the top of the script and in any READMEthat lists prerequisites.## 4. Cross-OS path and tool differences- Use `Join-Path` (PowerShell) or path-library functions instead of hardcoded `\` or `/` separators.- `sed -i` differs: GNU `sed -i 's/x/y/' file` vs BSD/macOS `sed -i '' 's/x/y/' file` (macOS requires the empty extension argument). Prefer `perl -i -pe` or a small Python/Node one-liner when a script must run on both.- Line endings: scripts checked out on Windows may get CRLF; `.sh` scripts with CRLF line endings fail with `bad interpreter` on Linux/macOS — check `.gitattributes` for `* text=auto` or explicit `eol=lf` rules on shell scripts.- `Test-Path`/`New-Item -ItemType Directory -Force` (PowerShell) vs `[ -d "$dir" ]`/`mkdir -p` (POSIX) — don't mix syntaxes within one script.## 5. When generating a new script1. Detect (or ask) which environment(s) it must run on.2. If the project already has a script for the same task in another shell (`.ps1` next to `.sh`), match its behavior and keep both updated.3. Default to the most restrictive compatible syntax (PS5.1 / POSIX sh) unless the task genuinely needs a newer feature — then state the requirement explicitly (`#Requires -Version 7.0`, `#!/usr/bin/env bash` with a documented bash-version minimum).4. Test the script (or at least syntax-check it: `pwsh -NoProfile -Command "& { . ./script.ps1 -WhatIf }"` style dry runs, or `bash -n script.sh`) before declaring it done.

Frequently asked questions