echo from php "as it goes" - buffer

what was the way to print results from a php script while it's printing stuff before the script ends? i tried to play with output buffer, putting sleep() between echos to test but the result is always showed after the script executes. Is it a browser-side thing too?

All you could do in your PHP script to try to flush all the current output to the user's browser is a call to ob_flush, but it actually depends on many other things as well.
The HTTP server has its own buffering, and the browser may not instantly render every packet it receives. It's like a long pipeline of buffers at different levels that all have to be flushed before you see anything in the browser, and the PHP output buffer is at the highest level.

yes you can do that this way
<?php
echo "hello senad";
flush();
sleep(20);
echo "meskin";
?>

PHP is server side. If you are making a web page, then the results will ALWAYS be shown on the client after the script ends and has been transmitted.
If you are running the script on your own computer, then I heard somewhere that one prints during execution and the other after the script is done. Try switching between print and echo and see how your results go.

There are 2 solutions:
1) Deactivate the output_buffering in php.ini
2) When using loops use this for example:
for ($i = 1; $i <= 3; $i++) {
echo md5(rand())."<br />";
flush();
ob_end_flush();
sleep(1);
}

PHP loads a page all at once then displays it. Use flush() to show output as the script loads.

Nice question.. when I want to do something like that (like loggin actions) I just use AJAX. And I know it's not probably what you wanted but hear me out.. I have had this problem as well 4 times so far and I've used AJAX and because of that I was able to put a preloader (which is really cool and helpful :))
By "use ajax" I mean if you have 4 actions to show up do 4 ajax requests. I know it's not the most elegant solution (as you do a lot of extra stuff) but it is a good design-wise solution.

Related

Way to get some sort of schedule in TCL without blocking on-going code

I need some sort of schedule thing to schedule a task to happen at x:y (12:00 for example) in Tcl.
The scenario is a router using Openwrt with Tcl 8.6.10 with limited RAM and storage where I have some sort of IRC client "bot" (using socket to connect). The "bot" was just a barebone that I modify to suit my needs. Most of the things work fine, except that I don't have way to schedule easily things. I wanted something like how eggdrop has "bind time" where the bind thing is "bind time flag "cron-style string" caller".
The "bot" scheme is like:
Main Tcl script:
<info+code to connect to IRC>
<while loop>
<some code in case of IRC disconnection>
<list of files with tcl code aka sub-scripts>
<usage of source based from a list of the filenames>
<code for error handling>
<end of while loop>
The list of files is source filelist.tcl, where filelist.tcl is a set var {filename1.tcl filename2.tcl...}. The filenamex.tcl has some basic code to respond to IRC server or IRC input from channels and reply to channels.
I can make some sort of schedule if I base a execution like if {[clock format [clock seconds] -format "%H:%M"]=="12:00"} {code to execute} and hopefully wait for a server ping/pong but that can lead to repeated code inside of the if body.
I been looking around and found a package called cron but I don't know how to use it correctly because there are not many examples and I don't know to use vwait properly and I don't want vwait to hang the bot waiting for a value to change. I also read about tcl threads for maybe parallel execution.
So I need some code inside of a sub-script that looks like (a package cron style):
#beginning of file
#add a task specifying hour and minute
task-at "12:00" proccaller
proc procname {optional} {
<some code to be executed at specific hour+time>
}
#end of file
I also don't know how to use after command to use it.
How can I accomplish I want?
Thanks for the replies and yes, it would help if I study event loops and coroutine, which probably comes next.
Some time has passed since I posted the question and kinda sorted the thing by creating a sub-script in a folder named scripts with the following structure:
#beginning of the script
if {![file exists executed]} {set executed "no"}
#the following clock instruction returns for example: Tuesday 22:14
switch -glob -- [clock format [clock seconds] -format "%A %H:%M"] {
"*12:00" - "*12:01" {
#Basic example of sending a message to the irc channel when it's midday
if {$executed=="no"} {
puts $fd "PRIVMSG #CODE :It's midday right now."
flush $fd
set executed "yes"
}
}
#...more time comparisions and code
default {set executed "no"}
}
#end of script
And the script is almost the top of the list of scripts to be loaded so if I wish to send some command down stream at giving time, the command can be executed.
There is double timings because the "bot" reacts, at least at minimum, to the irc server's ping which happens each 90 seconds and it may skip some minutes.
This is not an answer but an unproper workaround.

How do I intercept the unbuffered output of a Proc::Async in Raku?

With a snippet like
# Contents of ./run
my $p = Proc::Async.new: #*ARGS;
react {
whenever Promise.in: 5 { $p.kill }
whenever $p.stdout { say "OUT: { .chomp }" }
whenever $p.ready { say "PID: $_" }
whenever $p.start { say "Done" }
}
executed like
./run raku -e 'react whenever Supply.interval: 1 { .say }'
I expected to see something like
PID: 1234
OUT: 0
OUT: 1
OUT: 2
OUT: 3
OUT: 4
Done
but instead I see
PID: 1234
OUT: 0
Done
I understand that this has to do with buffering: if I change that command into something like
# The $|++ disables buffering
./run perl -E '$|++; while(1) { state $i; say $i++; sleep 1 }'
I get the desired output.
I know that TTY IO::Handle objects are unbuffered, and that in this case the $*OUT of the spawned process is not one. And I've read that IO::Pipe objects are buffered "so that a write without a read doesn't immediately block" (although I cannot say I entirely understand what this means).
But no matter what I've tried, I cannot get the unbuffered output stream of a Proc::Async. How do I do this?
I've tried binding an open IO::Handle using $proc.bind-stdout but I still get the same issue.
Note that doing something like $proc.bind-stdout: $*OUT does work, in the sense that the Proc::Async object no longer buffers, but it's also not a solution to my problem, because I cannot tap into the output before it goes out. It does suggest to me that if I can bind the Proc::Async to an unbuffered handle, it should do the right thing. But I haven't been able to get that to work either.
For clarification: as suggested with the Perl example, I know I can fix this by disabling the buffering on the command I'll be passing as input, but I'm looking for a way to do this from the side that creates the Proc::Async object.
You can set the .out-buffer of a handle (such as $*OUT or $*ERR) to 0:
$ ./run raku -e '$*OUT.out-buffer = 0; react whenever Supply.interval: 1 { .say }'
PID: 11340
OUT: 0
OUT: 1
OUT: 2
OUT: 3
OUT: 4
Done
Proc::Async itself isn't performing buffering on the received data. However, spawned processes may do their own depending on what they are outputting to, and that's what is being observed here.
Many programs make decisions about their output buffering (among other things, such as whether to emit color codes) based on whether the output handle is attached to a TTY (a terminal). The assumption is that a TTY means a human is going to be watching the output, and thus latency is preferable to throughput, so buffering is disabled (or restricted to line buffering). If, on the other hand, the output is going to a pipe or a file, then the assumption is that latency is not so important, and buffering is used to achieve a significant throughput win (a lot less system calls to write data).
When we spawn something with Proc::Async, the standard output of the spawned process is bound to a pipe - which is not a TTY. Thus the invoked program may use this to decide to apply output buffering.
If you're willing to have another dependency, then you can invoke the program via. something that fakes up a TTY, such as unbuffer (part of the expect package, it seems). Here's an example of a program that is suffering from buffering:
my $proc = Proc::Async.new: 'raku', '-e',
'react whenever Supply.interval(1) { .say }';
react whenever $proc.stdout {
.print
}
We only see a 0 and then have to wait a long time for more output. Running it via unbuffer:
my $proc = Proc::Async.new: 'unbuffer', 'raku', '-e',
'react whenever Supply.interval(1) { .say }';
react whenever $proc.stdout {
.print
}
Means that we see a number output every second.
Could Raku provide a built-in solution to this some day? Yes - by doing the "magic" that unbuffer itself does (I presume allocating a pty - kind of a fake TTY). This isn't trivial - although it is being explored by the libuv developers; at least so far as Rakudo on MoarVM goes, the moment there's a libuv release available offering such a feature, we'll work on exposing it.

Simple program that reads and writes to a pipe

Although I am quite familiar with Tcl this is a beginner question. I would like to read and write from a pipe. I would like a solution in pure Tcl and not use a library like Expect. I copied an example from the tcl wiki but could not get it running.
My code is:
cd /tmp
catch {
console show
update
}
proc go {} {
puts "executing go"
set pipe [open "|cat" RDWR]
fconfigure $pipe -buffering line -blocking 0
fileevent $pipe readable [list piperead $pipe]
if {![eof $pipe]} {
puts $pipe "hello cat program!"
flush $pipe
set got [gets $pipe]
puts "result: $got"
}
}
go
The output is executing go\n result:, however I would expect that reading a value from the pipe would return the line that I have sent to the cat program.
What is my error?
--
EDIT:
I followed potrzebie's answer and got a small example working. That's enough to get me going. A quick workaround to test my setup was the following code (not a real solution but a quick fix for the moment).
cd /home/stephan/tmp
catch {
console show
update
}
puts "starting pipe"
set pipe [open "|cat" RDWR]
fconfigure $pipe -buffering line -blocking 0
after 10
puts $pipe "hello cat!"
flush $pipe
set got [gets $pipe]
puts "got from pipe: $got"
Writing to the pipe and flushing won't make the OS multitasking immediately leave your program and switch to the cat program. Try putting after 1000 between the puts and the gets command, and you'll see that you'll probably get the string back. cat has then been given some time slices and has had the chance to read it's input and write it's output.
You can't control when cat reads your input and writes it back, so you'll have to either use fileevent and enter the event loop to wait (or periodically call update), or periodically try reading from the stream. Or you can keep it in blocking mode, in which case gets will do the waiting for you. It will block until there's a line to read, but meanwhile no other events will be responded to. A GUI for example, will stop responding.
The example seem to be for Tk and meant to be run by wish, which enters the event loop automatically at the end of the script. Add the piperead procedure and either run the script with wish or add a vwait command to the end of the script and run it with tclsh.
PS: For line-buffered I/O to work for a pipe, both programs involved have to use it (or no buffering). Many programs (grep, sed, etc) use full buffering when they're not connected to a terminal. One way to prevent them to, is with the unbuffer program, which is part of Expect (you don't have to write an Expect script, it's a stand-alone program that just happens to be included with the Expect package).
set pipe [open "|[list unbuffer grep .]" {RDWR}]
I guess you're executing the code from http://wiki.tcl.tk/3846, the page entitled "Pipe vs Expect". You seem to have omitted the definition of the piperead proc, indeed, when I copy-and-pasted the code from your question, I got an error invalid command name "piperead". If you copy-and-paste the definition from the wiki, you should find that the code works. It certainly did for me.

Capturing output from WshShell.Exec using Windows Script Host

I wrote the following two functions, and call the second ("callAndWait") from JavaScript running inside Windows Script Host. My overall intent is to call one command line program from another. That is, I'm running the initial scripting using cscript, and then trying to run something else (Ant) from that script.
function readAllFromAny(oExec)
{
if (!oExec.StdOut.AtEndOfStream)
return oExec.StdOut.ReadLine();
if (!oExec.StdErr.AtEndOfStream)
return "STDERR: " + oExec.StdErr.ReadLine();
return -1;
}
// Execute a command line function....
function callAndWait(execStr) {
var oExec = WshShell.Exec(execStr);
while (oExec.Status == 0)
{
WScript.Sleep(100);
var output;
while ( (output = readAllFromAny(oExec)) != -1) {
WScript.StdOut.WriteLine(output);
}
}
}
Unfortunately, when I run my program, I don't get immediate feedback about what the called program is doing. Instead, the output seems to come in fits and starts, sometimes waiting until the original program has finished, and sometimes it appears to have deadlocked. What I really want to do is have the spawned process actually share the same StdOut as the calling process, but I don't see a way to do that. Just setting oExec.StdOut = WScript.StdOut doesn't work.
Is there an alternate way to spawn processes that will share the StdOut & StdErr of the launching process? I tried using "WshShell.Run(), but that gives me a "permission denied" error. That's problematic, because I don't want to have to tell my clients to change how their Windows environment is configured just to run my program.
What can I do?
You cannot read from StdErr and StdOut in the script engine in this way, as there is no non-blocking IO as Code Master Bob says. If the called process fills up the buffer (about 4KB) on StdErr while you are attempting to read from StdOut, or vice-versa, then you will deadlock/hang. You will starve while waiting for StdOut and it will block waiting for you to read from StdErr.
The practical solution is to redirect StdErr to StdOut like this:
sCommandLine = """c:\Path\To\prog.exe"" Argument1 argument2"
Dim oExec
Set oExec = WshShell.Exec("CMD /S /C "" " & sCommandLine & " 2>&1 """)
In other words, what gets passed to CreateProcess is this:
CMD /S /C " "c:\Path\To\prog.exe" Argument1 argument2 2>&1 "
This invokes CMD.EXE, which interprets the command line. /S /C invokes a special parsing rule so that the first and last quote are stripped off, and the remainder used as-is and executed by CMD.EXE. So CMD.EXE executes this:
"c:\Path\To\prog.exe" Argument1 argument2 2>&1
The incantation 2>&1 redirects prog.exe's StdErr to StdOut. CMD.EXE will propagate the exit code.
You can now succeed by reading from StdOut and ignoring StdErr.
The downside is that the StdErr and StdOut output get mixed together. As long as they are recognisable you can probably work with this.
Another technique which might help in this situation is to redirect the standard error stream of the command to accompany the standard output.
Do this by adding "%comspec% /c" to the front and "2>&1" to the end of the execStr string.
That is, change the command you run from:
zzz
to:
%comspec% /c zzz 2>&1
The "2>&1" is a redirect instruction which causes the StdErr output (file descriptor 2) to be written to the StdOut stream (file descriptor 1).
You need to include the "%comspec% /c" part because it is the command interpreter which understands about the command line redirect. See http://technet.microsoft.com/en-us/library/ee156605.aspx
Using "%comspec%" instead of "cmd" gives portability to a wider range of Windows versions.
If your command contains quoted string arguments, it may be tricky to get them right:
the specification for how cmd handles quotes after "/c" seems to be incomplete.
With this, your script needs only to read the StdOut stream, and will receive both standard output and standard error.
I used this with "net stop wuauserv", which writes to StdOut on success (if the service is running)
and StdErr on failure (if the service is already stopped).
First, your loop is broken in that it always tries to read from oExec.StdOut first. If there is no actual output then it will hang until there is. You wont see any StdErr output until StdOut.atEndOfStream becomes true (probably when the child terminates). Unfortunately, there is no concept of non-blocking I/O in the script engine. That means calling read and having it return immediately if there is no data in the buffer. Thus there is probably no way to get this loop to work as you want. Second, WShell.Run does not provide any properties or methods to access the standard I/O of the child process. It creates the child in a separate window, totally isolated from the parent except for the return code. However, if all you want is to be able to SEE the output from the child then this might be acceptable. You will also be able to interact with the child (input) but only through the new window (see SendKeys).
As for using ReadAll(), this would be even worse since it collects all the input from the stream before returning so you wouldn't see anything at all until the stream was closed. I have no idea why the example places the ReadAll in a loop which builds a string, a single if (!WScript.StdIn.AtEndOfStream) should be sufficient to avoid exceptions.
Another alternative might be to use the process creation methods in WMI. How standard I/O is handled is not clear and there doesn't appear to be any way to allocate specific streams as StdIn/Out/Err. The only hope would be that the child would inherit these from the parent but that's what you want, isn't it? (This comment based upon an idea and a little bit of research but no actual testing.)
Basically, the scripting system is not designed for complicated interprocess communication/synchronisation.
Note: Tests confirming the above were performed on Windows XP Sp2 using Script version 5.6. Reference to current (5.8) manuals suggests no change.
Yes, the Exec function seems to be broken when it comes to terminal output.
I have been using a similar function function ConsumeStd(e) {WScript.StdOut.Write(e.StdOut.ReadAll());WScript.StdErr.Write(e.StdErr.ReadAll());} that I call in a loop similar to yours. Not sure if checking for EOF and reading line by line is better or worse.
You might have hit the deadlock issue described on this Microsoft Support site.
One suggestion is to always read both from stdout and stderr.
You could change readAllFromAny to:
function readAllFromAny(oExec)
{
var output = "";
if (!oExec.StdOut.AtEndOfStream)
output = output + oExec.StdOut.ReadLine();
if (!oExec.StdErr.AtEndOfStream)
output = output + "STDERR: " + oExec.StdErr.ReadLine();
return output ? output : -1;
}

How to monitor a text file in realtime [closed]

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For debugging purposes in a somewhat closed system, I have to output text to a file.
Does anyone know of a tool that runs on windows (console based or not) that detects changes to a file and outputs them in real-time?
I like tools that will perform more than one task, Notepad++ is a great notepad replacement and has a Document Monitor plugin (installs with standard msi) that works great. It also is portable so you can have it on a thumb drive for use anywhere.
For a command line option, PowerShell (which is really a new command line) has a great feature already mentioned.
Get-Content someFile.txt -wait
But you can also filter at the command line using a regular expression
Get-Content web.log -wait | where { $_ -match "ERROR" }
Tail for Win32
Apache Chainsaw - used this with log4net logs, may require file to be in a certain format
When using Windows PowerShell you can do the following:
Get-Content someFile.txt -wait
I use "tail -f" under cygwin.
I use BareTail for doing this on Windows. It's free and has some nice features, such as tabs for tailing multiple files and configurable highlighting.
Tail is the best answer so far.
If you don't use Windows, you probably already have tail.
If you do use Windows, you can get a whole slew of Unix command line tools from here. Unzip them and put them somewhere in your PATH.
Then just do this at the command prompt from the same folder your log file is in:
tail -n 50 -f whatever.log
This will show you the last 50 lines of the file and will update as the file updates.
You can combine grep with tail with great results - something like this:
tail -n 50 -f whatever.log | grep Error
gives you just lines with "Error" in it.
Good luck!
FileSystemWatcher works a treat, although you do have to be a little careful about duplicate events firing - 1st link from Google - but bearing that in mind can produce great results.
Late answer, though might be helpful for someone -- LOGEXPERT seems to be interesting tail utility for windows.
Try SMSTrace from Microsoft (now called CMTrace, and directly available in the Start Menu on some versions of Windows)
Its a brilliant GUI tool that monitors updates to any text file in real time, even if its locked for writing by another file.
Don't be fooled by the description, its capable of monitoring any file, including .txt, .log or .csv.
Its ability to monitor locked files is extremely useful, and is one of the reasons why this utility shines.
One of the nicest features is line coloring. If it sees the word "ERROR", the line becomes red. If it sees the word "WARN", the line becomes yellow. This makes the logs a lot easier to follow.
I have used FileSystemWatcher for monitoring of text files for a component I recently built. There may be better options (I never found anything in my limited research) but that seemed to do the trick nicely :)
Crap, my bad, you're actually after a tool to do it all for you..
Well if you get unlucky and want to roll your own ;)
Yor can use the FileSystemWatcher in System.Diagnostics.
From MSDN:
public class Watcher
{
public static void Main()
{
Run();
}
[PermissionSet(SecurityAction.Demand, Name="FullTrust")]
public static void Run()
{
string[] args = System.Environment.GetCommandLineArgs();
// If a directory is not specified, exit program.
if(args.Length != 2)
{
// Display the proper way to call the program.
Console.WriteLine("Usage: Watcher.exe (directory)");
return;
}
// Create a new FileSystemWatcher and set its properties.
FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = args[1];
/* Watch for changes in LastAccess and LastWrite times, and
the renaming of files or directories. */
watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
| NotifyFilters.FileName | NotifyFilters.DirectoryName;
// Only watch text files.
watcher.Filter = "*.txt";
// Add event handlers.
watcher.Changed += new FileSystemEventHandler(OnChanged);
watcher.Created += new FileSystemEventHandler(OnChanged);
watcher.Deleted += new FileSystemEventHandler(OnChanged);
watcher.Renamed += new RenamedEventHandler(OnRenamed);
// Begin watching.
watcher.EnableRaisingEvents = true;
// Wait for the user to quit the program.
Console.WriteLine("Press \'q\' to quit the sample.");
while(Console.Read()!='q');
}
// Define the event handlers.
private static void OnChanged(object source, FileSystemEventArgs e)
{
// Specify what is done when a file is changed, created, or deleted.
Console.WriteLine("File: " + e.FullPath + " " + e.ChangeType);
}
private static void OnRenamed(object source, RenamedEventArgs e)
{
// Specify what is done when a file is renamed.
Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath);
}
}
You can also follow this link Watching Folder Activity in VB.NET
Snake Tail. It is a good option.
http://snakenest.com/snaketail/
Just a shameless plug to tail onto the answer, but I have a free web based app called Hacksaw used for viewing log4net files. I've put in an auto refresh options so you can give yourself near real time updates without having to refresh the browser all the time.
Yeah I've used both Tail for Win32 and tail on Cygwin. I've found both to be excellent, although I prefer Cygwin slightly as I'm able to tail files over the internet efficiently without crashes (Tail for Win32 has crashed on me in some instances).
So basically, I would use tail on Cygwin and redirect the output to a file on my local machine. I would then have this file open in Vim and reload (:e) it when required.
+1 for BareTail. I actually use BareTailPro, which provides real-time filtering on the tail with basic search strings or search strings using regex.
To make the list complete here's a link to the GNU WIN32 ports of many useful tools (amongst them is tail).
GNUWin32 CoreUtils
Surprised no one has mentioned Trace32 (or Trace64). These are great (free) Microsoft utilities that give a nice GUI and highlight any errors, etc. It also has filtering and sounds like exactly what you need.
Here's a utility I wrote to do just that:
It uses a FileSystemWatcher to look for changes in log files within local folders or network shares (don't have to be mounted, just provide the UNC path) and appends the new content to the console.
on github: https://github.com/danbyrne84/multitail
http://www.danielbyrne.net/projects/multitail
Hope this helps
#echo off
set LoggingFile=C:\foo.txt
set lineNr=0
:while1
for /f "usebackq delims=" %%i in (`more +%lineNr% %LoggingFile%`) DO (
echo %%i
set /a lineNr+=1
REM Have an appropriate stop condition here by checking i
)
goto :while1
A command prompt way of doing it.
FileMon is a free stand alone tool that can detect all kinds of file access. You can filter out any unwanted. It does not show you the data that has actually changed though.
I second "tail -f" in cygwin. I assume that Tail for Win32 will accomplish the same thing.
Tail for Win32
I did a tiny viewer by my own:
https://github.com/enexusde/Delphi/wiki/TinyLog

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