which.js
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var common = require('./common');
var fs = require('fs');
var path = require('path');
common.register('which', _which, {
allowGlobbing: false,
});
// XP's system default value for PATHEXT system variable, just in case it's not
// set on Windows.
var XP_DEFAULT_PATHEXT = '.com;.exe;.bat;.cmd;.vbs;.vbe;.js;.jse;.wsf;.wsh';
// Cross-platform method for splitting environment PATH variables
function splitPath(p) {
if (!p) return [];
if (common.platform === 'win') {
return p.split(';');
} else {
return p.split(':');
}
}
function checkPath(pathName) {
return fs.existsSync(pathName) && !fs.statSync(pathName).isDirectory();
}
//@
//@ ### which(command)
//@
//@ Examples:
//@
//@ ```javascript
//@ var nodeExec = which('node');
//@ ```
//@
//@ Searches for `command` in the system's PATH. On Windows, this uses the
//@ `PATHEXT` variable to append the extension if it's not already executable.
//@ Returns string containing the absolute path to the command.
function _which(options, cmd) {
if (!cmd) common.error('must specify command');
var pathEnv = process.env.path || process.env.Path || process.env.PATH;
var pathArray = splitPath(pathEnv);
var where = null;
// No relative/absolute paths provided?
if (cmd.search(/\//) === -1) {
// Search for command in PATH
pathArray.forEach(function (dir) {
if (where) return; // already found it
var attempt = path.resolve(dir, cmd);
if (common.platform === 'win') {
attempt = attempt.toUpperCase();
// In case the PATHEXT variable is somehow not set (e.g.
// child_process.spawn with an empty environment), use the XP default.
var pathExtEnv = process.env.PATHEXT || XP_DEFAULT_PATHEXT;
var pathExtArray = splitPath(pathExtEnv.toUpperCase());
var i;
// If the extension is already in PATHEXT, just return that.
for (i = 0; i < pathExtArray.length; i++) {
var ext = pathExtArray[i];
if (attempt.slice(-ext.length) === ext && checkPath(attempt)) {
where = attempt;
return;
}
}
// Cycle through the PATHEXT variable
var baseAttempt = attempt;
for (i = 0; i < pathExtArray.length; i++) {
attempt = baseAttempt + pathExtArray[i];
if (checkPath(attempt)) {
where = attempt;
return;
}
}
} else {
// Assume it's Unix-like
if (checkPath(attempt)) {
where = attempt;
return;
}
}
});
}
// Command not found anywhere?
if (!checkPath(cmd) && !where) return null;
where = where || path.resolve(cmd);
return where;
}
module.exports = _which;