If a single dash is specified as the argument, it will be replaced by the value of `OLDPWD`.

The `OLDPWD` is set by `cd` command and it is the previous working directory.

`cd -` returns to the directory you were previously.

For instance:

&lt;pre&gt;
marcelo@marcelo:~$ cd /opt
marcelo@marcelo:/opt$ cd /usr/bin
marcelo@marcelo:/usr/bin$ cd -
/opt
marcelo@marcelo:/opt$ 
&lt;/pre&gt;

I was in /opt, changed to /usr/bin, and then went back to /opt with `cd -`

`cd -` brings you back to the last directory.

    $ cd ~/Desktop
    $ pwd
    /Users/daknok/Desktop
    $ cd /
    $ pwd
    /
    $ cd -
    $ pwd
    /Users/daknok/Desktop

`cd -` returns to the previous directory you were in.

Say I&#39;m in `/usr/` and I type `cd /var/local/someplace/else`

Then I use `cd -` I&#39;ll return to `/usr`

From the manual

&gt; An argument of - is equivalent to $OLDPWD.  If a non-empty directory
&gt; name from CDPATH is used, or if - is the first argument, and the
&gt; directory change is successful, the absolute pathname of the new 
&gt; working  directory is written to the standard output.  The return
&gt; value is true if the directory was successfully changed; false
&gt; otherwise

Therefore the `-` is equivalent to the `$OLDPWD`, which holds the last directory which the shell was in, and is set by the previous `cd` invocation.

From the man found here : http://ss64.com/bash/cd.html

    Quickly get back
    $ cd - 

cd - bring you back to the last directory you were.
e.g.

    cd ~/Documents
    cd ~
    cd /

Now you are in &#39;/&#39;, and if you run &#39;cd -&#39; you will be in &#39;~&#39;. BTW, run &#39;cd -&#39; once again, you will return to &#39;/&#39; but not &#39;~/Documents&#39;


“ Current Directory  “ Is what  the bash cd  terminal command means. It means “ keep me in this directory “ 





I&#39;m trying to get a CSS animation property to stay after completing, is this possible?

This is what I&#39;m trying to achieve...

The element should be hidden when the user lands on the page, after 3 seconds (or whatever), it should fade in and once the animation has completed it should stay there.

Here is a fiddle attempt...
http://jsfiddle.net/GZx6F/

Here is the code for preservation...

    &lt;h2&gt;Test&lt;/h2&gt;

    &lt;style&gt;
	@keyframes fadeIn {
		0% {
			opacity: 0;
		}
		100% {
			opacity: 0.9;
		}
	}
		
	h2 {
		animation: fadeIn 1s ease-in-out 3s;
	}
    &lt;/style&gt;

I know how to do this with jQuery.. it would be like this...

    &lt;h2&gt;test&lt;/h2&gt;

    &lt;script&gt;
      $(document).ready(function(){
        $(&#39;h2&#39;).hide().delay(3000).fadeIn(3000)
      });
    &lt;/script&gt;



CSS Animation property stays after animating

Does anybody know how to set padding between the ActionBar&#39;s home icon and the title?


Padding between ActionBar&#39;s home icon and title

In a bash shell script today I noticed the below command at the end of the script. I know what is `cd` but I am unaware of the significance of a dash after it.

    cd -

What does this mean? Google naively truncates the `-` so I am unable to find its answer.

What does &#39;cd -&#39; stand for?

In a bash shell script today I noticed the below command at the end of the script. I know what is <code>cd</code> but I am unaware of the significance of a dash after it.
<pre><code class="hljs language-bash">cd -
</code></pre>
What does this mean? Google naively truncates the <code>-</code> so I am unable to find its answer.

How to count all files inside a folder, its subfolder and all . The count should not include folder count.

I want to do it in MAC

How to count all files inside a folder, its subfolder and all . The count should not include folder count

I often find myself with a file that has one number per line. I end up importing it in excel to view things like median, standard deviation and so forth.

Is there a command line utility in linux to do the same? I usually need to find the average, median, min, max and std deviation.


command line utility to print statistics of numbers in linux

If I have a text file with a separate command on each line how would I make terminal run each line as a command? I just don&#39;t want to have to copy and paste 1 line at a time. It doesn&#39;t HAVE to be a text file... It can be any kind of file that will work.

`example.txt`:
    
    sudo command 1
    sudo command 2
    sudo command 3

Run text file as commands in Bash

I know that this is not something that should ever be done, but is there a way to use the slash character that normally separates directories within a filename in Linux?


Is it possible to use &quot;/&quot; in a filename?

If I have a class Foo in namespace bar:

    namespace bar
    {
        class Foo { ... }
    };

I can then:

    using Baz = bar::Foo;

and now it is just like I defined the class in my namespace with the name Baz.

Is it possible to do the same for functions?

    namespace bar
    {
        void f();
    }

And then:

    using g = bar::f; // error: ‘f’ in namespace ‘bar’ does not name a type

What is the cleanest way to do this?

The solution should also hold for template functions.

__Definition:__ If some entity B is an __alias__ of A, than if any or all usages (not declarations or definitions of course) of A are replaced by B in the source code than the (stripped) generated code remains the same.  For example `typedef A B` is an alias.  `#define B A` is an alias (at least).  `T&amp; B = A` is not an alias, B can effectively implemented as an indirect pointer, wheres an &quot;unaliased&quot; A can use &quot;immediate semantics&quot;.


C++11: How to alias a function?

I have a problem concerning storing the output of a command inside a variable within a bash script.  
I know in general there are two ways to do this

either

    foo=$(bar)
    # or
    foo=`bar`

but for the Java version query, this doesn&#39;t seem to work.

I did:

    version=$(java --version)

This doesn&#39;t store the value inside the var. It even still prints it, which really shouldn&#39;t be the case.

I also tried redirecting output to a file but this also fails.

Bash script store command output into variable

Lets say I have a shell / bash script named `test.sh` with:

    #!/bin/bash
    
    TESTVARIABLE=hellohelloheloo
    ./test2.sh

My `test2.sh` looks like this:


    #!/bin/bash
    
    echo ${TESTVARIABLE}

This does not work. I do not want to pass all variables as parameters since imho this is overkill.

Is there a different way?

Pass all variables from one shell script to another?

I would like to execute a number of `bash` commands from a `Rakefile`.

I have tried the following in my `Rakefile` 

    task :hello do
      %{echo &quot;World!&quot;}
    end

but upon executing `rake hello` there is no output?
How do I execute bash commands from a Rakefile?


**NOTE**:This is not a duplicate as it&#39;s specifically asking how to execute bash commands from a _Rakefile_.

Execute bash commands from a Rakefile

I have been developing a script on my linux box for quite some time, and wanted to run it on my Mac as well.

I thought that the functions on the Mac were the same as the functions on linux, but today I realized it was wrong. I knew that fewer functions existed on the Mac, but I thought that the functions that did exist, had the same implementation.

This problem is specifically in regards to the `date` command.

When I run the command on my linux machine with the parameter to provide some time in nanoseconds, I get the correct result, but when I run it on my mac, it does not have that option.
   
    Linux-Machine&gt; date +%N
    55555555555 #Current time in nanoseconds
    Mac-Machine&gt; date +%N
    N

How do I go about getting the current time in nanoseconds as a bash command on the Mac?

Worst case is I create a small piece of code that calls a system function in C or something and then call it within my script.

Any help is much appreciated!

Date command does not follow Linux specifications (Mac OS X Lion)


    find . -type f | xargs file | grep text | cut -d&#39;:&#39; -f1 | xargs grep -l &quot;TEXTSEARCH&quot; {}

it&#39;s a good solution? for find TEXTSEARCH recursively in only textual files

grep only text files

I have a directory containing several files, some of which have spaces in their names:

    Test workspace/
    Another directory/
    file1.ext
    file2.ext
    demo 2012-03-23.odp

I use GNU&#39;s `$(wildcard)` command on this directory, and then iterate over the result using `$(foreach)`, printing everything out. Here&#39;s the code:

    FOO := $(wildcard *)
    $(info FOO = $(FOO))
    $(foreach PLACE,$(FOO),$(info PLACE = $(PLACE)))

Here&#39;s what I would expect to see printed out:

    Test workspace
    Another directory
    file1.ext
    file2.ext
    demo 2012-03-23.odp

Here&#39;s what I would actually get:

    Test
    workspace
    Another
    directory
    file1.ext
    file2.ext
    demo
    2012-03-23.odp

The latter is obviously of no use to me. The &lt;a href=&quot;http://www.gnu.org/software/make/manual/html_node/Wildcard-Function.html&quot;&gt;documentation&lt;/a&gt; for `$(wildcard)` flat-out states that it returns a &quot;space-separated list of names&quot; but completely fails to acknowledge the huge problems this raises. Nor does the &lt;a href=&quot;http://www.gnu.org/savannah-checkouts/gnu/make/manual/html_node/Foreach-Function.html&quot;&gt;documentation&lt;/a&gt; for `$(foreach)`.

Is it possible to work around this? If so, how? Renaming every file and directory to remove the spaces is not an option.

Can GNU make handle filenames with spaces?

In the following script I get an error: 

&gt; syntax error: unexpected end of file

What is this error how can I resove it? It is pointing at the line whee the function is called.

    #!/bin/sh
    
    expected_diskusage=&quot;264&quot;
    expected_dbconn=&quot;25&quot;
    expected_httpdconn=&quot;20&quot;
    expected_cpuusage=&quot;95&quot;
    #expected_fd=&quot;100&quot;
    
    httpdconn=`ps -ef|grep -i httpd|grep -v grep|wc -l` #httpd connections
    cpu_usage=`ps aux|awk &#39;NR &gt; 0 { s +=$3 }; END {print s}&#39;`
    disk_usage=`df -h|awk {&#39;print $2&#39;}|head -n3|awk &#39;NF{s=$0}END{print s}&#39;`
    #db_connections=`mysql -uroot -pexxxxxx -s -N -e &quot;show processlist&quot;|wc -l`
    
    db_connections=6
    cld_alert()
    {
        nwconn=$1
        cpu_usage=$2
        disk_usage=$3
        db_connections=$4
        message=$5
        `touch /tmp/alert.txt &amp;&amp; &gt; /tmp/alert.txt`
        date=`date`
        echo -e &quot;$date\n&quot; &gt; /tmp/alert.txt
        echo -e &quot;$message&quot; &gt;&gt; /tmp/alert.txt
        path=&quot;/proc/$httpd/fd/&quot;;
        cd $path
        tfd=`ls -l|wc -l`;
        sfd=`ls -ltr|grep sock|wc -l`;
        echo &quot;Total fds: $tfd&quot; &gt;&gt; /tmp/alert.txt
        echo &quot;Socket fds: $sfd&quot; &gt;&gt; /tmp/alert.txt
        echo &quot;Other fds: $[$tfd - $sfd]&quot; &gt;&gt; /tmp/alert.txt
    
    
        freememory=`vmstat | awk &#39;{if (NR == 3) print &quot;Free Memory:&quot;\$4}&#39;`;
        echo &quot;Free memory :$freememory&quot; &gt;&gt; /tmp/alert.txt
        Bufferedmemory=`vmstat | awk &#39;{if (NR == 3) print &quot;Buffered Memory:&quot;\$5}&#39;`;
        echo &quot;Buffered memory $Bufferedmemory&quot; &gt;&gt; /tmp/alert.txt
        CacheMemory=`vmstat | awk &#39;{if (NR == 3) print &quot;Cache Memory:&quot;\$6}&#39;`;
        echo &quot;Cache memory : $CacheMemory&quot; &gt;&gt; /tmp/alert.txt
        sshconn=`netstat -an|grep 22|wc -l`  #ssh connections
        httpsconn=`netstat -an|grep 443|wc -l`  #https connections
        wwwconn=`netstat -an|grep 80|wc -l`  #www connections
        echo &quot;Disk usage is $disk_usage&quot; &gt;&gt; /tmp/alert.txt
        echo &quot;DB connections $db_connections&quot; &gt;&gt; /tmp/alert.txt
        echo &quot;Network connections $nwconn&quot; &gt;&gt; /tmp/alert.txt
        echo &quot;CPU Usage: $cpu_usage&quot; &gt;&gt; /tmp/alert.txt
        topsnapshot=`top -n 1 -b`
        echo &quot;===========================TOP COMMAND    SNAPSHOT====================================================&quot;;
        echo &quot;$topsnapshot&quot; &gt;&gt; /tmp/alert.txt
        echo&quot;==================PS COMMAND SNAPSHOT==============================================================&quot;
        entireprocesslist=`ps -ef`
        echo &quot;$entireprocesslist&quot; &gt;&gt; /tmp/alert.txt
    
    
        echo Hello hi&quot;&quot;;
    
    }
    
    
    
    message=&quot;&quot;
    if [ ${disk_usage%?} -le $expected_diskusage ]    ##{x%?} Removes last character
    then
        echo &quot;disk usage exceeded&quot;;
        message=&quot;Disk usage limit exceeded \nCurrent disk usage is $disk_usage\nConfigured disk usage is    $expected_diskusage\n\n\n\n\n&quot;;
        #Checking for CPU usage
        if [ $cpu_usage -ge $expected_cpuusage]    ##{x%?}
        then
            echo &quot;CPU usage exceeded&quot;;
            if [ $message -ne &quot;&quot; ]
            then
                message=&quot;$message\n\nCPU usage exceeded configured usage limit \nCurrent CPU usage is $cpu_usage\nConfigured CPU usage is $expected_cpuusage\n\n\n\n\n&quot;;
            else
                message=&quot;CPU usage exceeded configured usage limit \nCurrent CPU usage is   $cpu_usage\nConfigured CPU usage is $expected_cpuusage\n\n\n\n\n&quot;;
            fi ;
        fi
        #Checking for httpd connections
        if [ $httpdconn -ge $expected_httpdconn]    ##{x%?}
        then
            echo &quot;HTTPD connections exceeded&quot;;
            if [ $message -ne &quot;&quot; ]
            then
                message=&quot;$message\n\nHTTPD connections exceeded configured usage limit \nCurrent HTTPD connections is $httpdconn\nConfigured HTTPD connection is $expected_httpdconn&quot;;
            else
                message=&quot;HTTPD connections exceeded configured usage limit \nCurrent HTTPD connections is $httpdconn\nConfigured HTTPD connection is $expected_httpdconn&quot;;
            fi ;
        fi ;
        message=&quot;$message\n\n\n\n\n&quot;;
        value=$(cld_alert $message $httpdconn $cpu_usage $disk_usage $db_connections)


Shell Script Syntax Error: Unexpected End of File

The title should say it all. I&#39;m looking for an equivalent to `${BASH_SOURCE[0]}` in zsh.

*Note:* I keep finding &quot;`$0` is equivalent to `${BASH_SOURCE[0]}`&quot; around the Internet, but this seems to be false: `$0` seems to be the name of the executing command. (It&#39;s `argv[0]`, which makes sense.) Echoing $0 in my script (`.zshrc`) gives `zsh` for `$0`, which isn&#39;t the same as what `${BASH_SOURCE[0]}` is. In fact, `${BASH_SOURCE[0]}` seems to work in `zsh`, except for inside `.zshrc` files.

*What I&#39;m really doing in my `.zshrc` (that isn&#39;t working):*

    echo ${BASH_SOURCE[0]}
    source `dirname $0`/common-shell-rc.sh

The source fails (`$0` is `zsh`) and the `echo` outputs a blank line.

**Edit:** &lt;strike&gt;apparently, for `$0` to work, I need the option `FUNCTION_ARGZERO` option set. Any way to test if this is set in a script? (so that I can temporarily set it)&lt;/strike&gt; It is apparently on unless you set `nofunction_argzero`, and it is on in my shell. Still get nothing for `$0`. (I think b/c I&#39;m not in a function.)

${BASH_SOURCE[0]} equivalent in zsh?

I have as bash shell script with header `#!/bin/bash -e`.

When I run the script, it will be interrupted after the `grep` command runs, but when I remove the parameter `-e`, then the script can be run normally. What is the meaning of parameter `-e`?

Content Type	Original Author	Original Content on Stackoverflow
Question	AppleGrew	View Question on Stackoverflow
Solution 1 - Linux	Sandro Munda	View Answer on Stackoverflow
Solution 2 - Linux	Marcelo Diniz	View Answer on Stackoverflow
Solution 3 - Linux	user1203803	View Answer on Stackoverflow
Solution 4 - Linux	Cfreak	View Answer on Stackoverflow
Solution 5 - Linux	phoxis	View Answer on Stackoverflow
Solution 6 - Linux	Michael Laffargue	View Answer on Stackoverflow
Solution 7 - Linux	Jie Zhang	View Answer on Stackoverflow
Solution 8 - Linux	TheHessian	View Answer on Stackoverflow

What does 'cd -' stand for?

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Padding between ActionBar's home icon and title

CSS Animation property stays after animating

Attributions