Commands

Quote and interpolate arguments

Use run program argument ... for an explicit command. Arguments can contain spaces without becoming multiple arguments, and RecurLoop expressions can be interpolated with {expression}.

import shell
var label = "release candidate"
run printf "%s\n" "{label}"
assert status == 0

This passes one value argument, release candidate, to printf. Quotes group an argument; they are not passed to the program. {label} evaluates a RecurLoop expression rather than a shell variable.

Select Shell syntax explicitly

Use shell when a program name overlaps a phrase in another vocabulary. A selector block applies that selection to its contents.

import shell
shell {
    printf "selected shell syntax\n"
}

Prefer run or an explicit selector in reusable code. Recognition of a bare program name depends on the active vocabulary.

Arguments are data

There is no automatic shell expansion of $NAME, command substitution or a shell script hidden inside a string. Use environment for process variables and Shell:Command:add for data assembled at runtime. To intentionally execute a shell script, invoke a shell explicitly and treat that script as code.