Use the `timeout` command:

    timeout 15s command

Note: on some systems you need to install `coreutils`, on others it&#39;s missing or has different command line arguments. See an alternate solution posted by @ArjunShankar . Based on it you can encapsulate that boiler-plate code and create your own portable `timeout` script or small C app that does the same thing.

Some machines don&#39;t have `timeout` installed/available. In that case, you could background the process; its PID then gets stored as `$!`; then sleep for the required amount of time, then kill it:

    some_command arg1 arg2 &amp;
    TASK_PID=$!
    sleep 15
    kill $TASK_PID

At [this URL][1] I find that there are mentioned, more than one solutions to make this happen.


  [1]: http://mywiki.wooledge.org/BashFAQ/068

A string length which contains one space is always equal to 1:

    alert(&#39;My str length: &#39; + str.length);

The space is a character, so:

    str = &quot;   &quot;;
    alert(&#39;My str length:&#39; + str.length); // My str length: 3

How can I make a distinction between an empty string and a string which contains only spaces? How can I detect a string which contain only spaces?

How to detect string which contains only spaces?

I am trying to design a library in F#. The library should be friendly for use from *both F# and C#*.

And this is where I&#39;m stuck a little bit.  I can make it F# friendly, or I can make it C# friendly, but the problem is how to make it friendly for both.

Here is an example.  Imagine I have the following function in F#:

&lt;!-- language: lang-ml --&gt;

    let compose (f: &#39;T -&gt; &#39;TResult) (a : &#39;TResult -&gt; unit) = f &gt;&gt; a

This is perfectly usable from F#:

&lt;!-- language: lang-ml --&gt;

    let useComposeInFsharp() =
        let composite = compose (fun item -&gt; item.ToString) (fun item -&gt; printfn &quot;%A&quot; item)
        composite &quot;foo&quot;
        composite &quot;bar&quot;

In C#, the `compose` function has the following signature:

&lt;!-- language: lang-cs --&gt;

    FSharpFunc&lt;T, Unit&gt; compose&lt;T, TResult&gt;(FSharpFunc&lt;T, TResult&gt; f, FSharpFunc&lt;TResult, Unit&gt; a);

But of course, I don&#39;t want `FSharpFunc` in the signature, what I want is `Func` and `Action` instead, like this:

&lt;!-- language: lang-cs --&gt;

    Action&lt;T&gt; compose2&lt;T, TResult&gt;(Func&lt;T, TResult&gt; f, Action&lt;TResult&gt; a);

To achieve this, I can create `compose2` function like this:

&lt;!-- language: lang-ml --&gt;

    let compose2 (f: Func&lt;&#39;T, &#39;TResult&gt;) (a : Action&lt;&#39;TResult&gt; ) = 
        new Action&lt;&#39;T&gt;(f.Invoke &gt;&gt; a.Invoke)

Now, this is perfectly usable in C#:

&lt;!-- language: lang-cs --&gt;

    void UseCompose2FromCs()
    {
        compose2((string s) =&gt; s.ToUpper(), Console.WriteLine);
    }

But now we have a problem using `compose2` from F#!  Now I have to wrap all standard F# `funs` into `Func` and `Action`, like this:

&lt;!-- language: lang-ml --&gt;

    let useCompose2InFsharp() =
        let f = Func&lt;_,_&gt;(fun item -&gt; item.ToString())
        let a = Action&lt;_&gt;(fun item -&gt; printfn &quot;%A&quot; item)
        let composite2 = compose2 f a

        composite2.Invoke &quot;foo&quot;
        composite2.Invoke &quot;bar&quot;

**The question:** How can we achieve first-class experience for the library written in F# for both F# and C# users?

So far, I couldn&#39;t come up with anything better than these two approaches:

0. Two separate assemblies: one targeted to F# users, and the second to C# users.
0. One assembly but different namespaces: one for F# users, and the second for C# users.

For the first approach, I would do something like this:

0. Create a F# project, call it FooBarFs and compile it into FooBarFs.dll.
    - Target the library purely to F# users.
    - Hide everything unnecessary from the .fsi files.

0. Create another F# project, call if FooBarCs and compile it into FooFar.dll
    - Reuse the first F# project at the source level.
    - Create .fsi file which hides everything from that project.
    - Create .fsi file which exposes the library in C# way, using C# idioms for name, namespaces, etc.
    - Create wrappers that delegate to the core library, doing the conversion where necessary.

I think the second approach with the namespaces can be confusing to the users, but then you have one assembly.  

**The question:** None of these are ideal, perhaps I am missing some kind of compiler flag/switch/attribute
or some kind of trick and there is a better way of doing this?

**The question:** has anyone else tried to achieve something similar and if so how did you do it?


EDIT: to clarify, the question is not only about functions and delegates but the overall experience of a C# user with an F# library. This includes namespaces, naming conventions, idioms and suchlike that are native to C#. Basically, a C# user shouldn&#39;t be able to detect that the library was authored in F#. And vice versa, an F# user should feel like dealing with a C# library.






-----------------
**EDIT 2:**

I can see from the answers and comments so far that my question lacks the necessary depth,
perhaps mostly due to use of only one example where interoperability issues between F# and C# 
arise, the issue of function values.  I think this is the most obvious example and so this
led me to use it to ask the question, but by the same token gave the impression that this is
the only issue I am concerned with.

Let me provide more concrete examples. I have read through the most excellent
[F# Component Design Guidelines](http://fsharp.org/specs/component-design-guidelines/)
document (many thanks @gradbot for this!). The guidelines in the document, if used, do address
some of the issues but not all.

The document is split into two main parts: 1) guidelines for targeting F# users; and 2) guidelines for
targeting C# users.  Nowhere does it even attempt to pretend that it is possible to have a uniform
approach, which exactly echoes my question: we can target F#, we can target C#, but what is the
practical solution for targeting both?

To remind, the goal is to have a library authored in F#, and which can be used *idiomatically* from
both F# and C# languages.

The keyword here is *idiomatic*. The issue is not the general interoperability where it is just possible
to use libraries in different languages.

Now to the examples, which I take straight from 
[F# Component Design Guidelines](http://fsharp.org/specs/component-design-guidelines/).


1.  Modules+functions (F#) vs Namespaces+Types+functions

    -   F#: Do use namespaces or modules to contain your types and modules.
        The idiomatic use is to place functions in modules, e.g.:

            // library
            module Foo
            let bar() = ...
            let zoo() = ...


            // Use from F#
            open Foo
            bar()
            zoo()


    -   C#: Do use namespaces, types and members as the primary organizational structure for your 
        components (as opposed to modules), for vanilla .NET APIs.


        This is incompatible with the F# guideline, and the example would need
        to be re-written to fit the C# users:

            [&lt;AbstractClass; Sealed&gt;]
            type Foo =
                static member bar() = ...
                static member zoo() = ...


        By doing so though, we break the idiomatic use from F# because
        we can no longer use `bar` and `zoo` without prefixing it with `Foo`.


2.  Use of tuples

    -   F#: Do use tuples when appropriate for return values.

    -   C#: Avoid using tuples as return values in vanilla .NET APIs.

3.  Async

    -   F#: Do use Async&lt;T&gt; for async programming at F# API boundaries.  

    -   C#: Do expose asynchronous operations using either the .NET asynchronous programming model 
        (BeginFoo, EndFoo), or as methods returning .NET tasks (Task&lt;T&gt;), rather than as F# Async&lt;T&gt; 
        objects.


4.  Use of `Option`

    -   F#: Consider using option values for return types instead of raising exceptions (for F#-facing code).

    -   Consider using the TryGetValue pattern instead of returning F# option values (option&lt;T&gt;) in vanilla 
        .NET APIs, and prefer method overloading over taking F# option values as arguments.


5.  Discriminated unions


    -   F#: Do use discriminated unions as an alternative to class hierarchies for creating tree-structured data

    -   C#: *no specific guidelines for this, but the concept of discriminated unions is foreign to C#*



6.  Curried functions

    -   F#: *curried functions are idiomatic for F#*

    -   C#: Do not use currying of parameters in vanilla .NET APIs.


7.  Checking for null values

    -   F#: *this is not idiomatic for F#*

    -   C#: Consider checking for null values on vanilla .NET API boundaries.


8.  Use of F# types `list`, `map`, `set`, etc

    -   F#: *it is idiomatic to use these in F#*

    -   C#: Consider using the .NET collection interface types IEnumerable&lt;T&gt; and IDictionary&lt;Key,Value&gt;
        for parameters and return values in vanilla .NET APIs. (*i.e. do not use F# `list`, `map`, `set`*)


9.  Function types (the obvious one)

    -   F#: *use of F# functions as values is idiomatic for F#, obviously*

    -   C#: Do use .NET delegate types in preference to F# function types in vanilla .NET APIs.


I think these should be sufficient to demonstrate the nature of my question.

Incidentally, the guidelines also have a partial answer:

&gt; ... a common implementation strategy when developing higher-order 
&gt; methods for vanilla .NET libraries is to author all the implementation using F# function types, and 
&gt; then create the public API using delegates as a thin fa&#231;ade atop the actual F# implementation.  


**To summarise.** 

There is one definite answer: *there are no compiler tricks that I missed*.

As per the guidelines doc, it seems that authoring for F# first and then creating
a facade wrapper for .NET is a reasonable strategy.

The question then remains regarding the practical implementation of this:

-   Separate assemblies? or

-   Different namespaces?

If my interpretation is correct, Tomas suggests that using separate namespaces should
be sufficient, and should be an acceptable solution.

I think I will agree with that given that the choice of namespaces is such that it
does not surprise or confuse the .NET/C# users, which means that the namespace
for them should probably look like it is the primary namespace for them.  The
F# users will have to take the burden of choosing F#-specific namespace.
For example:

-   FSharp.Foo.Bar  -&gt; namespace for F# facing the library

-   Foo.Bar         -&gt; namespace for .NET wrapper, idiomatic for C#




Best approach for designing F# libraries for use from both F# and C#

&gt; **Possible Duplicate:**  
&gt; [Bash script that kills a child process after a given timeout](https://stackoverflow.com/questions/5161193/bash-script-that-kills-a-child-process-after-a-given-timeout)  

&lt;!-- End of automatically inserted text --&gt;

Is there a way to write a shell script that would execute a certain command for 15 seconds, then kill the command?

I have tried sleep, wait and ping but maybe I am using them wrong.

How to run a process with a timeout in Bash?

> Possible Duplicate: 
> <a href="https://stackoverflow.com/questions/5161193/bash-script-that-kills-a-child-process-after-a-given-timeout" target="_blank" rel="noopener noreferrer">Bash script that kills a child process after a given timeout</a>

Is there a way to write a shell script that would execute a certain command for 15 seconds, then kill the command?
I have tried sleep, wait and ping but maybe I am using them wrong.

The [list of MongoDB GUI client apps on the official site](http://www.mongodb.org/display/DOCS/Admin+UIs) is outdated: some clients are not supported, some are heavily bound to .NET and not runnable on Linux. And all of them lack the ability to edit stored documents (i.e. provide read-only access).

I need a GUI client that:

 1. Works on Linux (but not web);
 2. Is free;
 3. Supports documents editing.

Is there an app which satisfies these requirements?

MongoDB GUI client (cross-platform or Linux)

I am running a putty client on a Windows machine to connect successfully to a Linux box. Now I want to be able to copy a file from the Linux machine under the path `/home/ubuntu/myfile` to `C:/Users/Anshul/Desktop` on my local computer. The user at the Windows machine is `anshul`. I am giving the following command on putty but it is not working:

    scp /home/ubuntu/myfile ip_address_of_windows_machine:C:/Users/Anshul/Desktop 

I think the path for the Windows machine is wrong. Please help as I have banged my head on a large number of forums but none seem to give correct path for Windows server. Don&#39;t suggest alternate options like `WinScp`

scp from Linux to Windows

I am on R version 2.13 and would like to update to a newer version in order to use some packages that depend on R&gt;= 2.14. 

I have the line to my sources.list file as found described [here][1].  I then navigate to the terminal and type:

    sudo apt-get update

and get the following error when trying to update R on the CRAN mirror closest to me:

&gt;Reading package lists... Done
&gt;
W: GPG error: http://lib.stat.cmu.edu oneiric/ Release: The following signatures couldn&#39;t be verified because the public key is not available: NO_PUBKEY 51716619E084DAB9

Any idea how to debug this error?


  [1]: http://cran.r-project.org/bin/linux/ubuntu/

Installing R from CRAN Ubuntu repository: No Public Key Error

When I try to download Java from Oracle I instead end up downloading a page telling me that I need agree to the OTN license terms.

&gt; # Sorry!
&gt; 
&gt; In order to download products from Oracle Technology Network you must agree to the OTN license terms.
&gt; 
&gt; Be sure that...
&gt; 
&gt; - Your browser has &quot;cookies&quot; and JavaScript enabled.
&gt; - You clicked on &quot;Accept License&quot; for the product you wish to download.
&gt; - You attempt the download within 30 minutes of accepting the license.

How can I download and install Java?

Downloading Java JDK on Linux via wget is shown license page instead

How do I install mbstring with PHP on CentOS 6.2

I&#39;ve tried:

    $ sudo yum install php-mbstring

    Loaded plugins: fastestmirror, security
    Loading mirror speeds from cached hostfile
     * base: mirror.net.cen.ct.gov
     * extras: centos.aol.com
     * updates: mirrors.seas.harvard.edu
    Setting up Install Process
    No package php-mbstring available.
    Error: Nothing to do

But no packages were found?

How to install PHP mbstring on CentOS 6.2

    wc -l file.txt

outputs number of lines and file name.

I need just the number itself (not the file name).

I can do this
    
     wc -l file.txt | awk &#39;{print $1}&#39;

But maybe there is a better way? 

How to get &quot;wc -l&quot; to print just the number of lines without file name?

I both love and hate writing Bash. I love that it&#39;s *so* streamlined for operating on files and working with processes (I agree with [this popular question](https://stackoverflow.com/questions/3637668/why-are-scripting-languages-e-g-perl-python-ruby-not-suitable-as-shell-lang) that it&#39;s way better in this regard than Python, Ruby, etc.), but I *hate* the syntax, particularly around conditionals, loops, etc.

(This is subjective, but I find it both confusing and annoying. E.g. `$var` when reading, but `var` when writing; writes silently fail if there are spaces around `=`; the double brackets in ifs when using regexp; double semicolons sometimes and single semicolons others; etc.)

As a huge fan of CoffeeScript, which compiles to JS, I&#39;ve been wondering: are there any languages that have the aesthetic/syntax of languages like Python/Ruby/CoffeeScript but which compile and run as Bash instead of one of those other runtimes?

E.g. I&#39;d love to be able to write mostly-Bash with just a bit simpler syntax:

    $AGGREGATE_FILENAME = &#39;allfiles.txt&#39;
    
    if not exists $AGGREGATE_FILENAME
        touch $AGGREGATE_FILENAME
    
    for $file in files/*
        cat $file &gt;&gt; $AGGREGATE_FILENAME
    
    switch $1
        case &#39;test&#39;
            run-tests
            echo &#39;Tests finished!&#39;
        case &#39;deploy&#39;
            echo &#39;Packaging...&#39;
            mv foo bar/
            deploy-bar

This is a super contrived example, and the syntax is a strawman (mostly inspired from CoffeeScript but keeping the essential Bash notions of first-class commands, separated from variables, and loose typing).

Anyway, just a question and food for thought. I&#39;d *love* to be able to write my scripts in something nicer than Bash. =) Thanks!

Are there any languages that compile to Bash?

When I use the [Mac OS X Terminal][1] to navigate to the folder with my Android Emulator and type `emulator`, I get:

&gt; command not found

Here&#39;s what happens:

    $ emulator
    -bash: emulator: command not found

How do I get it to work?

  [1]: https://en.wikipedia.org/wiki/Terminal_%28OS_X%29


I get &#39;Command Not Found&#39; when I try to run Android Emulator on Mac OS X

I found the below script that lists the branches by date. How do I filter this to exclude newer branches and feed the results into the Git delete command?

    for k in $(git branch | sed /\*/d); do 
      echo &quot;$(git log -1 --pretty=format:&quot;%ct&quot; $k) $k&quot;
    done | sort -r | awk &#39;{print $2}&#39;


Delete all branches that are more than X days/weeks old

I know I can use `cd` command to change my working directory in bash.  

But if I do this command:

    cd SOME_PATH &amp;&amp; run_some_command

Then the working directory will be changed permanently. Is there some way to change the working directory just temporarily like this?

    PWD=SOME_PATH run_some_command

Temporarily change current working directory in bash to run a command

I am calling a series of links using the [`file_get_contents()`](http://php.net/file_get_contents) method in a loop. Each link may take more than 15 minutes to process. Now, I worry about whether PHP&#39;s `file_get_contents()` has a timeout period?

If yes, it will time out with a call and move to next link. I don&#39;t want to call the next link without the prior one finishing.

So, please tell me whether `file_get_contents()` has a timeout period. The file which contains the `file_get_contents()` is set to [`set_time_limit()`](http://php.net/set_time_limit) to zero (unlimited).

Does file_get_contents() have a timeout setting?

I&#39;m trying to cut down the time ssh is trying to open a connection to a host. If I put for example `ssh www.google.com` it takes very long until the prompt comes back.

I read about using `ssh -o ConnectTimeout=10 www.google.com` instead, but even this takes very long. Is there maybe a number of attemps I can modify to decrease the blocking time?

Set SSH connection timeout

As far as I can tell, there&#39;s no way to know that it&#39;s specifically a timeout that has occurred. Am I not looking in the right place, or am I missing something bigger?

    string baseAddress = &quot;http://localhost:8080/&quot;;
    var client = new HttpClient() 
    { 
        BaseAddress = new Uri(baseAddress), 
        Timeout = TimeSpan.FromMilliseconds(1) 
    };
    try
    {
        var s = client.GetAsync(&quot;&quot;).Result;
    }
    catch(Exception e)
    {
        Console.WriteLine(e.Message);
        Console.WriteLine(e.InnerException.Message);
    }

This returns:

&gt;One or more errors occurred.
&gt;
&gt;A task was canceled.

How can I tell when HttpClient has timed out?

I have a small issue that I&#39;m not quite sure how to solve. Here is a minimal example:

### What I have

    scan_process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    while(some_criterium):
        line = scan_process.stdout.readline()
        some_criterium = do_something(line)

### What I would like

    scan_process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    while(some_criterium):
        line = scan_process.stdout.readline()
        if nothing_happens_after_10s:
            break
        else:
            some_criterium = do_something(line)

I read a line from a subprocess and do something with it. How can I exit if no line arrived after a fixed time interval?






Timeout on subprocess readline in Python

Is there any way I can make the error 504 gateway timeout longer if so how and where is the file to change it located. I am using nginx on centos 6

Content Type	Original Author	Original Content on Stackoverflow
Question	AlanF	View Question on Stackoverflow
Solution 1 - Linux	Karoly Horvath	View Answer on Stackoverflow
Solution 2 - Linux	ArjunShankar	View Answer on Stackoverflow

How to run a process with a timeout in Bash?

Linux Problem Overview

Linux Solutions

Solution 1 - Linux

Solution 2 - Linux

Best approach for designing F# libraries for use from both F# and C#

How to detect string which contains only spaces?

Attributions