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💬 Escaping/quoting

Array syntax

When using the array syntax, arguments are automatically escaped. They can contain any character, including spaces, tabs and newlines. However, they cannot contain null bytes: binary inputs should be used instead.

import {execa} from 'execa';

await execa('npm', ['run', 'task with space']);

Template string syntax

The same applies when using the template string syntax. However, spaces, tabs and newlines must use ${}.

await execa`npm run ${'task with space'}`;

User-defined input

The above syntaxes allow the file and its arguments to be user-defined by passing a variable.

import {execa} from 'execa';

const file = 'npm';
const commandArguments = ['run', 'task with space'];
await execa`${file} ${commandArguments}`;

await execa(file, commandArguments);

If the file and/or multiple arguments are supplied as a single string, parseCommandString() can split it into an array.

import {execa, parseCommandString} from 'execa';

const commandString = 'npm run task';
const commandArray = parseCommandString(commandString);
await execa`${commandArray}`;

const [file, ...commandArguments] = commandArray;
await execa(file, commandArguments);

Spaces are used as delimiters. They can be escaped with a backslash.

await execa`${parseCommandString('npm run task\\ with\\ space')}`;

Shells

Shells (Bash, cmd.exe, etc.) are not used unless the shell option is set. This means shell-specific syntax has no special meaning and does not need to be escaped:

  • Quotes: "value", 'value', $'value'
  • Characters: $variable, &&, ||, ;, |
  • Globbing: *, **
  • Expressions: $?, ~
// This prints `$TASK_NAME`, not `build`
await execa({env: {TASK_NAME: 'build'}})`echo $TASK_NAME`;

If you do set the shell option, arguments will not be automatically escaped anymore. Instead, they will be concatenated as a single string using spaces as delimiters.

await execa({shell: true})`npm ${'run'} ${'task with space'}`;
// Is the same as:
await execa({shell: true})`npm run task with space`;

Therefore, you need to manually quote the arguments, using the shell-specific syntax.

await execa({shell: true})`npm ${'run'} ${'"task with space"'}`;
// Is the same as:
await execa({shell: true})`npm run "task with space"`;

Sometimes a shell command is passed as argument to an executable that runs it indirectly. In that case, that shell command must quote its own arguments.

const command = 'npm run "task with space"';
await execa`ssh host ${command}`;

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