aaac7fed
 liuqimichale
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var common = require('./common');
var fs = require('fs');
var path = require('path');
common.register('which', _which, {
allowGlobbing: false,
cmdOptions: {
'a': 'all',
},
});
// 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) {
return p ? p.split(path.delimiter) : [];
}
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 isWindows = process.platform === 'win32';
var pathEnv = process.env.path || process.env.Path || process.env.PATH;
var pathArray = splitPath(pathEnv);
var queryMatches = [];
// No relative/absolute paths provided?
if (cmd.indexOf('/') === -1) {
// Assume that there are no extensions to append to queries (this is the
// case for unix)
var pathExtArray = [''];
if (isWindows) {
// 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;
pathExtArray = splitPath(pathExtEnv.toUpperCase());
}
// Search for command in PATH
for (var k = 0; k < pathArray.length; k++) {
// already found it
if (queryMatches.length > 0 && !options.all) break;
var attempt = path.resolve(pathArray[k], cmd);
if (isWindows) {
attempt = attempt.toUpperCase();
}
var match = attempt.match(/\.[^<>:"/\|?*.]+$/);
if (match && pathExtArray.indexOf(match[0]) >= 0) { // this is Windows-only
// The user typed a query with the file extension, like
// `which('node.exe')`
if (checkPath(attempt)) {
queryMatches.push(attempt);
break;
}
} else { // All-platforms
// Cycle through the PATHEXT array, and check each extension
// Note: the array is always [''] on Unix
for (var i = 0; i < pathExtArray.length; i++) {
var ext = pathExtArray[i];
var newAttempt = attempt + ext;
if (checkPath(newAttempt)) {
queryMatches.push(newAttempt);
break;
}
}
}
}
} else if (checkPath(cmd)) { // a valid absolute or relative path
queryMatches.push(path.resolve(cmd));
}
if (queryMatches.length > 0) {
return options.all ? queryMatches : queryMatches[0];
}
return options.all ? [] : null;
}
module.exports = _which;
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