Shelllike

Shelllike is an adjective applied in computing to describe interfaces, languages, or tools that resemble a command-line shell in their interaction model. A shelllike system typically accepts textual commands, supports interactive use, and provides features derived from traditional computing shells, such as command interpretation, variable expansion, and scripting capabilities, often with support for pipelines and redirection.

Core features commonly associated with shelllike systems include: command invocation by name, arguments, environment variables; quoting rules; variable assignment and expansion; command substitution; control constructs such as if, for, while; pipelines that connect the standard output of one command to the input of another; redirection of input and output; path and glob expansion; history and aliases.

Shelllike interfaces are used beyond real shells: embedded terminals in text editors, database shells (like psql), or domain-specific languages implemented with shell-like syntax for automation. They are designed to be familiar to users of Unix-like shells, but implementations may be simplified or restricted for security and portability.

Examples commonly described as shelllike include POSIX sh compatible syntaxes in many scripting languages, shells such as Bash, Zsh, and Fish, and embedded shell interfaces in applications. The term also applies to DSLs and REPLs that adopt shell-like semantics without being full shells.

Design considerations for shelllike systems include balancing expressiveness with safety, often by sandboxing, restricting builtins, or using restricted execution environments to minimize risk when executing commands.