Editing Comparison of command shells (section)

=== Autocorrection ===
[[File:Zsh autocompletion and autocorrection demo.gif|thumb|upright=2.0|Zsh autocompletion and autocorrection demo for a [[telnet]] program.]]
When a command line does not match a command or arguments directly, spell checking can automatically correct common typing mistakes (such as [[case sensitivity]], missing letters). There are two approaches to this; the shell can either suggest probable corrections upon command invocation, or this can happen earlier as part of a completion or autosuggestion.

The [[tcsh]] and [[zsh]] shells feature optional spell checking/correction, upon command invocation.

Fish does the autocorrection upon completion and autosuggestion. The feature is therefore not in the way when typing out the whole command and pressing enter, whereas extensive use of the tab and right-arrow keys makes the shell mostly case insensitive.

The PSReadLine<ref name="PSReadLine"/> PowerShell module (which is shipped with version 5.0) provides the option to specify a CommandValidationHandler ScriptBlock which runs before submitting the command. This allows for custom correcting of commonly mistyped commands, and verification before actually running the command.