The code says everything:

    max@serv$ chmod 777 .

Okay, it doesn&#39;t say everything.

In UNIX and Linux, the ability to remove a file is **not** determined by the access bits of that file. It is determined by the access bits of the directory which contains the file.

Think of it this way -- deleting a file doesn&#39;t modify that file. You aren&#39;t writing to the file, so why should &quot;w&quot; on the file matter? Deleting a file requires editing the directory that points to the file, so you need &quot;w&quot; on the that directory.

D[](http://www.google.com)ear all, I wonder what is the type of `null` literal in C#?

In Java, the `null` literal [is of the special _null type_](http://java.sun.com/docs/books/jls/second_edition/html/typesValues.doc.html#11128):

&gt; There is also a special _null type_, the type of the expression `null`, which has no name. Because the null type has no name, it is impossible to declare a variable of the null type or to cast to the null type. The null reference is the only possible value of an expression of null type. The null reference can always be cast to any reference type.

In C++11, there is `nullptr` (the recommended version of the old buddy `NULL`), which [is of type `std::nullptr_t`](http://en.cppreference.com/w/cpp/language/nullptr).

I searched MSDN about C#, but the [specification](http://msdn.microsoft.com/en-us/library/ms228593.aspx) doesn&#39;t seem to say anything about that.

What is the type of null literal?

How are the constructors called during serialization and deserialization

1. When there is one class implementing serializable?
2. When there is parent/child relationship and only child implements serializable?
3. When there is parent/child relationship and both parent and child implements serializable?

How are constructors called during serialization and deserialization?

        max@serv$ whoami
        max
        max@serv$ ls -la ./defines.php 
        -rwxrwxrwx 1 max max 1985 2011-11-16 02:01 ./defines.php
        max@serv$ chmod 0777 ./defines.php 
        max@serv$ rm ./defines.php 
        rm: cannot remove `./defines.php&#39;: Permission denied
        max@serv$

 

How can I delete this file?

rm: cannot remove: Permission denied

<pre><code class="hljs language-bash"> max@serv$ whoami
 max
 max@serv$ ls -la ./defines.php 
 -rwxrwxrwx 1 max max 1985 2011-11-16 02:01 ./defines.php
 max@serv$ chmod 0777 ./defines.php 
 max@serv$ rm ./defines.php 
 rm: cannot remove `./defines.php': Permission denied
 max@serv$
</code></pre>
How can I delete this file?

I have multiple files which I want to concat with `cat`.
Let&#39;s say 

    File1.txt 
    foo
    
    File2.txt
    bar
    
    File3.txt
    qux

I want to concat so that the final file looks like:

    foo
    
    bar
    
    qux

Instead of this with usual `cat File*.txt &gt; finalfile.txt` 

 

    foo
    bar 
    qux

What&#39;s the right way to do it?

Concatenating Files And Insert New Line In Between Files

I have written the same program (open text file and display contents) in C and C++. Now am doing the same in Python (on a Linux machine).

In the C programs I used the code:

    if (argc != 2) {
        /* exit program */
    }

**Question: What is used in Python to check the number of arguments**

    #!/usr/bin/python
    import sys
    try:
    	in_file = open(sys.argv[1], &quot;r&quot;)
    except:
    	sys.exit(&quot;ERROR. Did you make a mistake in the spelling&quot;)
    text = in_file.read()
    print text
    in_file.close()

Current output:

    ./python names.txt = Displays text file (correct)
    ./python nam = error message: stated from the sys.ext line (correct)
    ./python = error message: stated from the sys.ext line (wrong: want it to be a
    separate error message stating *no file name input*)

Does Python have an argc argument?

I&#39;m in college, and for a project we&#39;re using C. We&#39;ve explored GCC and Clang, and Clang appears to be much more user friendly than GCC.  As a result, I&#39;m wondering what the advantages or disadvantages are to using clang, as opposed to GCC, for developing in C and C++ on Linux? 

In my case this would be used for student level programs, not production. 

If I use Clang, should I debug with GDB and use GNU Make, or use another debugger and make utility?

Clang vs GCC for my Linux Development project

I would like to redirect the output generated from a background application in Linux to /dev/null.

I am using kate text editor and it prints all the debug messages on the terminal which I would like to redirect to /dev/null.

Any idea how to do it ?

Thanks

How to redirect the output of an application in background to /dev/null

I want to check the operating system (on the computer where the script runs).

I know I can use `os.system(&#39;uname -o&#39;)` in Linux, but it gives me a message in the console, and I want to write to a variable.

It will be okay if the script can tell if it is Mac, Windows or Linux. How can I check it? 

How do I check the operating system in Python?

All of the lines with comments in a file begin with `#`. How can I delete all of the lines (and only those lines) which begin with `#`? Other lines containing `#`, but not at the beginning of the line should be ignored.

Delete all lines beginning with a # from a file

How can I add numbers to the beginning of every line in a file?

E.g.:

&lt;pre&gt;
This is
the text
from the file.
&lt;/pre&gt;

Becomes:

&lt;pre&gt;
000000001 This is
000000002 the text
000000003 from the file.
&lt;/pre&gt;


Add numbers to the beginning of every line in a file

I want to write code like this:

    command=&quot;some command&quot;

    safeRunCommand $command

    safeRunCommand() {
       cmnd=$1

       $($cmnd)

       if [ $? != 0 ]; then
          printf &quot;Error when executing command: &#39;$command&#39;&quot;
          exit $ERROR_CODE
       fi
    }

But this code does not work the way I want. Where did I make the mistake?



Get the exit code for a command in Bash and KornShell (ksh)

Well, I&#39;m a linux newbie, and I&#39;m having an issue with a simple bash script.

I&#39;ve got a program that adds to a log file while it&#39;s running. Over time that log file gets huge. I&#39;d like to create a startup script which will rename and move the log file before each run, effectively creating separate log files for each run of the program. Here&#39;s what I&#39;ve got so far:

[pastebin](http://pastebin.com/mDVuSZ5k)

    DATE=$(date +&quot;%Y%m%d%H%M&quot;)
    mv server.log logs/$DATE.log
    echo program

When run, I see this:

    : command not found
    program

When I cd to the logs directory and run dir, I see this:

    201111211437\r.log\r

What&#39;s going on? I&#39;m assuming there&#39;s some syntax issue I&#39;m missing, but I can&#39;t seem to figure it out.


----------

UPDATE: Thanks to shellter&#39;s comment below, I&#39;ve found the problem to be due to the fact that I&#39;m editing the .sh file in Notepad++ in windows, and then sending via ftp to the server, where I run the file via ssh. After running dos2unix on the file, it works.

New question: How can I save the file correctly in the first place, to avoid having to perform this fix every time I resend the file?

Adding timestamp to a filename with mv in BASH

I want to display a string in Bash  like this  

    I&#39;m a student

Of course you can do it like this 

    echo &quot;I&#39;m a student&quot;

But how to accomplish this while using single quote around the string ? 



Content Type	Original Author	Original Content on Stackoverflow
Question	Nikolay Baluk	View Question on Stackoverflow
Solution 1 - Linux	Robᵩ	View Answer on Stackoverflow

rm: cannot remove: Permission denied

Linux Problem Overview

Linux Solutions

Solution 1 - Linux

How are constructors called during serialization and deserialization?

What is the type of null literal?

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