appium安卓7.0以上报错：Original error: Command failed: ps: uiautomator

解决方法：步骤如下

1.找到appium的安装目录下的adb.js文件，目录为：Appium\node_modules\appium\node_modules\appium-adb\lib 

2.打开adb.js，找到如下代码：

ADB.prototype.shell = function (cmd, cb) {if (cmd.indexOf('"') === -1) {cmd = '"' + cmd + '"';}var execCmd = 'shell ' + cmd;this.exec(execCmd, cb);};

在上段代码后添加如下代码：

ADB.prototype.shell_grep = function (cmd, grep, cb) {if (cmd.indexOf('"') === -1) {cmd = '"' + cmd + '"';}var execCmd = 'shell ' + cmd + '| grep ' + grep;this.exec(execCmd, cb);};

　　

3.找到如下代码：

ADB.prototype.getPIDsByName = function (name, cb) {logger.debug("Getting all processes with '" + name + "'");this.shell("ps '" + name + "'", function (err, stdout) {if (err) return cb(err);stdout = stdout.trim();var procs = [];var outlines = stdout.split("\n");outlines.shift();_.each(outlines, function (outline) {if (outline.indexOf(name) !== -1) {procs.push(outline);}});if (procs.length < 1) {logger.debug("No matching processes found");return cb(null, []);}var pids = [];_.each(procs, function (proc) {var match = /[^\t ]+[\t ]+([0-9]+)/.exec(proc);if (match) {pids.push(parseInt(match[1], 10));}});if (pids.length !== procs.length) {var msg = "Could not extract PIDs from ps output. PIDS: " +JSON.stringify(pids) + ", Procs: " + JSON.stringify(procs);return cb(new Error(msg));}cb(null, pids);});};

把如上代码注释掉，添加如下代码：

ADB.prototype.getPIDsByName = function (name, cb) {logger.debug("Getting all processes with '" + name + "'");this.shell_grep("ps", name, function (err, stdout) {if (err) {logger.debug("No matching processes found");return cb(null, []);}var pids = [];_.each(procs, function (proc) {var match = /[^\t ]+[\t ]+([0-9]+)/.exec(proc);if (match) {pids.push(parseInt(match[1], 10));}});if (pids.length !== procs.length) {var msg = "Could not extract PIDs from ps output. PIDS: " +JSON.stringify(pids) + ", Procs: " + JSON.stringify(procs);return cb(new Error(msg));}cb(null, pids);});};

　　

4.重启appium，问题解决