stderr

I'm trying to capture the stdout from a spawn ed child_process in node.js (0.10.29). Right now I'm just trying with ping The following code doesn't print (but does ping) var exec = require('child_process').exec; var spawn = require('child_process').spawn; var util = require('util') var ping = spawn('ping', ['127.0.0.1'], {stdio: 'pipe'}); ping.stdout.on('data', function(data){ util.print(data); }) ping.stderr.on('data', function(data){ util.print(data); }) If I change stdio: 'pipe' to stdio: 'inherit' and get rid of the stdout/stderr hooks like so: var ping = spawn('ping', ['127.0.0.2'],

import subprocess # # 默认接受['程序名','参数']的列表；shell=True表示直接调用系统的shell来执行字符串参数 # print(subprocess.run('dir',shell=True)) # 执行指定的命令，等待命令执行完成后返回一个包含执行结果的CompletedProcess类的实例。 # print(subprocess.call('dir',shell=True)) # 执行指定的命令，返回命令执行状态，其功能类似于os.system(cmd) # print(subprocess.check_call('dir',shell=True)) #执行指定的命令，如果执行成功则返回状态码，否则抛出异常。其功能等价于subprocess.run(..., check=True)。 # print(subprocess.check_output('dir',shell=True)) #执行指定的命令，如果执行状态码为0则返回命令执行结果(二进制字节形式的)，否则抛出异常。 # print(subprocess.getoutput('dir')) # 接收字符串格式的命令，执行命令并返回执行结果，其功能类似于os.popen(cmd).read()和commands.getoutput(cmd)。 # print(subprocess

What is the difference between them and how are they used? Can anyone point me to examples? Specifically, how do you "write" to the stream in both cases and how do you recover and output (i.e. to the screen) the text that had been written to it? Also, the "screen" output is itself a stream right? Maybe I don't understand streams well enough. This can also be saved to a file of course, I know. Would all of these use fprintf / fscanf , etc? cerr is the C++ stream and stderr is the C file handle, both representing the standard error output. You write to them the same way you write to other

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I am desperately trying to output a PDF generated by phantomJS to stdout like here What I am getting is an empty PDF file, although it is not 0 in size, it displays a blank page. var page = require('webpage').create(), system = require('system'), address; address = system.args[1]; page.paperSize = {format: 'A4'}; page.open(address, function (status) { if (status !== 'success') { console.log('Unable to load the address!'); phantom.exit(); } else { window.setTimeout(function () { page.render('/dev/stdout', { format: 'pdf' }); phantom.exit(); }

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: Long story short: pythonw.exe does nothing, python.exe accepts nothing (which one should I use?) test.py: print "a" CMD window: C:\path>pythonw.exe test.py C:\path> C:\path>python.exe test.py File "C:\path\test.py", line 7 print "a" ^ SyntaxError: invalid syntax C:\path> Please tell me what I'm doing terrible wrong. 回答1: If you don't want a terminal window to pop up when you run your program use pythonw.exe ; Otherwise, use python.exe Regarding the syntax error: print is now a function in 3.x So use instead: print("a") 回答2: To summarize and

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I'm using subprocess to run hive commands in python, but am getting empty results. If i run the same commands from hive CLI, am getting results. query = "set hive.cli.print.header=true;use mydb;describe table1;" process = subprocess.Popen( ["ssh", "hadoop" , "hive", "-e", "%r" % query], stdout = subprocess.PIPE, stderr = subprocess.PIPE ) data = [line.split('\t') for line in process.stdout] cols = list(itertools.chain.from_iterable(data[:1])) df = pd.DataFrame(data[1:], columns = cols) print "==>"+df+"<----" It's returning empty dataframe.

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: def captureOutput(self, func, *args, **kwargs): pass sys.stdout.flush() sys.stderr.flush() (outfd, fn) = tempfile.mkstemp() fout = os.fdopen(outfd, 'r') os.unlink(fn) (errfd, fn) = tempfile.mkstemp() ferr = os.fdopen(errfd, 'r') os.unlink(fn) try: oldstdout = os.dup(sys.stdout.fileno()) oldstderr = os.dup(sys.stderr.fileno()) os.dup2(outfd, sys.stdout.fileno()) os.dup2(errfd, sys.stderr.fileno()) try: ret = func(*args, **kwargs) finally: sys.stderr.flush() sys.stdout.flush() os.dup2(oldstdout, sys.stdout.fileno()) os.close(oldstdout) os.dup2

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I'm using Python 2.7.6 and IDLE on Windows 7. I have 2 Python scripts: script.py: import subprocess, os, sys print("hello 1") mypath = os.path.abspath(__file__) mydir = os.path.dirname(mypath) start = os.path.join(mydir, "script2.py") subprocess.call([sys.executable, start, "param"]) print("bye 1") and script2.py that is being called by the previous script: import sys print "hello 2" print (sys.argv[1]) print "bye 2" If I run script.py with cmd.exe shell I get the expected result: C:\tests>python ./script.py hello 1 hello 2 param bye 2 bye 1

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I run Appium server: I try to run this code to post to Appium server: public class AndroidTest { private AppiumDriver driver; @Before public void setUp() throws Exception { // File classpathRoot = new File(System.getProperty("user.dir")); // File appDir = new File(classpathRoot, "../../../data/app/"); // File app = new File(appDir, "Facebook.apk"); DesiredCapabilities capabilities = new DesiredCapabilities(); capabilities.setCapability(CapabilityType.BROWSER_NAME, ""); capabilities.setCapability("deviceName","10.0.0.9:5555"); capabilities