try `pcregrep` instead of regular `grep`:

    pcregrep -M &quot;pattern1.*\n.*pattern2&quot; filename

the `-M` option allows it to match across multiple lines, so you can search for newlines as `\n`.

`grep` patterns are matched against individual lines so there is no way for a pattern to match a newline found in the input.

However you can find empty lines like this:

    grep &#39;^$&#39; file
    grep &#39;^[[:space:]]*$&#39; file # include white spaces 

Thanks to @jarno I know about the -z option and I found out that when using GNU grep with the -P option, *matching against `\n` is possible*. :)

**Example:**

```
grep -zoP &#39;foo\n\K.*&#39;&lt;&lt;&lt;$&#39;foo\nbar&#39;
```

Result:
```
bar
```

**Example that involves matching everything including newlines:**

`.*` will not match newlines. To match everything including newlines, use&lt;sup&gt;1&lt;/sup&gt; `(.|\n)*`:

```
grep -zoP &#39;foo\n\K(.|\n)*&#39;&lt;&lt;&lt;$&#39;foo\nbar\nqux&#39;
```

Result:
```
bar
qux
```


&lt;sup&gt;1&lt;/sup&gt; Seen here: https://stackoverflow.com/a/33418344


You can use this way...

    grep -P &#39;^\s$&#39; file

- `-P` is used for Perl regular expressions (an extension to POSIX `grep`).
- `\s` match the white space characters; if followed by `*`, it matches an empty line also.
- `^` matches the beginning of the line. `$` matches the end of the line.  

As for the workaround (without using non-portable `-P`), you can temporary replace a new-line character with the different one and change it back, e.g.:

    grep -o &quot;_foo_&quot; &lt;(paste -sd_ file) | tr -d &#39;_&#39;

Basically it&#39;s looking for exact match `_foo_` where `_` means `\n` (so `__` = `\n\n`). You don&#39;t have to translate it back by `tr &#39;_&#39; &#39;\n&#39;`, as each pattern would be printed in the new line anyway, so removing `_` is enough.

just found

    grep $&#39;\r&#39;

It&#39;s using `$&#39;\r&#39;` for c-style escape in Bash.

in [this article][1]


  [1]: https://superuser.com/questions/194668/grep-to-find-files-that-contain-m-windows-carriage-return

I currently use the following but it ALWAYS prompts me to manually type the password. Is there any way to pass it in on the command line when launching the executable?

    mysqladmin processlist -u root -p

Is there a way to pass the DB user password into the command line tool mysqladmin?

What *exactly* happens when you call `setRetainInstance(true)` on a `Fragment`? The documentation is virtually non-existent and this seems like a very important function. Specifically I want to know how much of this sequence (that I made up) is true:

&gt; 1. The user rotates the device.
&gt; 2. The fragment is detached from the `Activity` and `Fragment.onDetach()` is called.
&gt; 3. The activity is destroyed; `Activity.onDestroy()` is called.
&gt; 4. The `Activity` java object is deleted (when possible, by the GC).
&gt; 5. A new `Activity` java object is created; its constructor, and `onCreate()` are called.
&gt; 6. In `Activity.onCreate()` we either have `setContentView(...)` which sets a layout containing a fragment, or we use `FragmentTransaction`
&gt; to add a fragment.
&gt; 7. I&#39;m really not sure about this, but I assume that android is smart enough to find the old fragment, and call `Fragment.onAttach()` to
&gt; reattach it to the new `Activity`
&gt; 8. Next (or before? who knows?) `Activity.onResume()` is called.

So is that correct? Is Android smart enough to find the old fragment, even if I explicitly use `FragmentTransaction.add(new MyFragment(), ...)` the first time? And if so, how do I avoid adding *another* fragment in `onCreate()`? Do I need to do something like this?:


		if (getSupportFragmentManager().findFragmentByTag(&quot;foo&quot;) == null)
		{
			FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
			ft.add(new FooFragment(), &quot;foo&quot;).commit();
		}


Further understanding setRetainInstance(true)

How to give a pattern for new line in grep?
New line at beginning, new line at end. Not the regular expression way. Something like \n.


How to give a pattern for new line in grep?

<p>How to give a pattern for new line in grep?
New line at beginning, new line at end. Not the regular expression way. Something like \n.</p>


How do I convert command-line arguments into a bash script array?

I want to take this:

    ./something.sh arg1 arg2 arg3

and convert it to 

    myArray=( arg1 arg2 arg3 )

so that I can use myArray for further use in the script.

This previous SO post comes close, but doesn&#39;t go into how to create an array: https://stackoverflow.com/questions/192249/how-do-i-parse-command-line-arguments-in-bash

I need to convert the arguments into a regular bash script array; I realize I could use other languages (Python, for instance) but need to do this in bash. I guess I&#39;m looking for an &quot;append&quot; function or something similar?

UPDATE: I also wanted to ask how to check for zero arguments and assign a default array value, and thanks to the answer below, was able to get this working:

    if [ &quot;$#&quot; -eq 0 ]; then
      myArray=( defaultarg1 defaultarg2 )
    else
      myArray=( &quot;$@&quot; )
    fi

Convert command line arguments into an array in Bash

I am trying to divide two image widths in a Bash script, but bash gives me `0` as the result:

    RESULT=$(($IMG_WIDTH/$IMG2_WIDTH))

I did study the Bash guide and I know I should use `bc`, in all examples in internet they use `bc`. In `echo` I tried to put the same thing in my `SCALE` but it didn&#39;t work.

Here is the example I found in the tutorials:

    echo &quot;scale=2; ${userinput}&quot; | bc 

How can I get Bash to give me a float like `0.5`?

How do I use floating-point arithmetic in bash?


    array=(a b c d)
I would like to add a character before each element of the array in order to have this

    array=(^a ^b ^c ^d)
An easy way to do that is to loop on array elements and change values one by one

    for i in &quot;${#array[@]}&quot;
    do
        array[i]=&quot;^&quot;array[i]
    done
But I would like to know if there is any way to do the same thing without looping on the array as I have to do the same instruction on all elements.

Thanks in advance.


How to change values of bash array elements without loop

While learning a bit about [tag:bash], I come to see four types of ways of working with `if` statements:

* Single Parenthesis - ( ... )
* Double Parenthesis - (( ... ))
* Single Square Bracket - [ ... ]
* Double Square Brackets - [[ ... ]]

What is the difference between Parenthesis and Square Brackets in bash.

Difference between parentheses and brackets in Bash conditionals

I want to format text as a table. I tried echoing with a `&#39;\t&#39;` separator, but it was misaligned.

Desired output:

    a very long string..........     112232432      anotherfield
    a smaller string                 123124343      anotherfield

How can I align the columns of tables in Bash?

Is there any grep option that let&#39;s me control total number of matches but stops at first match on each file?

Example:


If I do this `grep -ri --include &#39;*.coffee&#39; &#39;re&#39; .` I get this:

    ./app.coffee:express = require &#39;express&#39;
    ./app.coffee:passport = require &#39;passport&#39;
    ./app.coffee:BrowserIDStrategy = require(&#39;passport-browserid&#39;).Strategy
    ./app.coffee:app = express()
    ./config.coffee:    session_secret: &#39;nyan cat&#39;

And if I do `grep -ri -m2 --include &#39;*.coffee&#39; &#39;re&#39; .`, I get this:

    ./app.coffee:config = require &#39;./config&#39;
    ./app.coffee:passport = require &#39;passport&#39;

But, what I really want is this output:

    ./app.coffee:express = require &#39;express&#39;
    ./config.coffee:    session_secret: &#39;nyan cat&#39;

Doing `-m1` does not work as I get this for `grep -ri -m1 --include &#39;*.coffee&#39; &#39;re&#39; .`

    ./app.coffee:express = require &#39;express&#39;

Tried not using grep e.g. this `find . -name &#39;*.coffee&#39; -exec awk &#39;/re/ {print;exit}&#39; {} \;` produced:
   
    config = require &#39;./config&#39;
        session_secret: &#39;nyan cat&#39;

**UPDATE: As noted below the GNU grep `-m` option treats counts per file whereas `-m` for BSD grep treats it as global match count**

How to match once per file in grep?

I am trying to output a string that contains everything between two words of a string:

input:

    &quot;Here is a String&quot;

output:

    &quot;is a&quot;

Using: 

    sed -n &#39;/Here/,/String/p&#39;

includes the endpoints, but I don&#39;t want to include them.



How to use sed/grep to extract text between two words?

How to grep in one file and execute for every match a command?

File:
    
    foo
    bar
    42
    foo
    bar

I want to execute to execute for example `date` for every match on `foo`.

Following try doesn&#39;t work:
 
    grep file foo | date %s.%N

How to do that?

How to grep and execute a command (for every match)

I know that, if I wanted to grep for a pattern only on files with certain extensions, I could do this:

    // searches recursively and matches case insensitively in only javascript files
    // for &quot;res&quot; from the current directory
    grep -iIr --include=*.js res ./

I&#39;ve been trying to search for a way to do this via git grep as well (to take advantage of git grep&#39;s speed from the indexes it stores with its tree), but to no avail. I saw [here][1] that excluding certain file types is not possible.


  [1]: http://git.661346.n2.nabble.com/git-grep-while-excluding-files-in-a-blacklist-td7195648.html

git grep by file extensions

     grep -i -A 5 -B 5 &#39;db_pd.Clients&#39;  eightygigsfile.sql

This has been running for an hour on a fairly powerful linux server which is otherwise not overloaded.
Any alternative to grep? Anything about my syntax that can be improved, (egrep,fgrep better?) 

The file is actually in a directory which is shared with a mount to another server but the actual diskspace is local so that shouldn&#39;t make any difference? 

the grep is grabbing up to 93% CPU

Grepping a huge file (80GB) any way to speed it up?

If there are two keywords then they must have their own meanings. So I want to know what makes them different and what their code is.

What is the difference between a &quot;line feed&quot; and a &quot;carriage return&quot;?

I&#39;m trying to remove all newline characters from a string. I&#39;ve read up on how to do it, but it seems that I for some reason am unable to do so. Here is step by step what I am doing:
 
    string1 = &quot;Hello \n World&quot;
    string2 = string1.strip(&#39;\n&#39;)
    print string2

And I&#39;m still seeing the newline character in the output. I&#39;ve tried with rstrip as well, but I&#39;m still seeing the newline. Could anyone shed some light on why I&#39;m doing this wrong? Thanks.


Remove all newlines from inside a string

Just quick one, but want to make sure I&#39;m catching cross platform variations.

I like to convert new lines entered into a text area into a [comma], so that the output can be represented on a single line, my question...

Currently, sending from google chrome, when I view the value, I find it uses `\r\n` for new lines. If I replace `\r\n` I know it will work for chrome on windows 7, but what about other platforms, are there variations on what other browsers will insert as a new line inside a text area?

What character represents a new line in a text area

I would like to output a progress indicator during my lengthy running algorithms. I can easily &quot;bubble up&quot; a progress value from within my algorithm (e.g. via invoking a provided function callback specifically for this purpose), but the difficulty is in the actual text output process. Every call to `print` creates a new line, and each prefixed with `[1]`.

**Is there a way to print at different moments in time, without introducing line breaks?**

To be concrete, I want to achieve an &quot;animation&quot; that would look like the following if observed at two different times.

    0%...

...

    0%...2%...4%...



How to output text in the R console without creating new lines?

To speed up some bash script execution, I would like to keep the result of a command in a variable using command substitution, but the command substitution replaces the `0x0A` newline character by a space. For example:

    a=`df -H`
or

    a=$( df -H )
When I want to process further `$a`, the newline characters are replaced by a space and all the lines are now on one line, which is much harder to grep:

    echo $a

What would be the easy tricks to avoid the newline character being removed by the command substitution?

Content Type	Original Author	Original Content on Stackoverflow
Question	tuxnani	View Question on Stackoverflow
Solution 1 - Bash	nullrevolution	View Answer on Stackoverflow
Solution 2 - Bash	arash kordi	View Answer on Stackoverflow
Solution 3 - Bash	rubystallion	View Answer on Stackoverflow
Solution 4 - Bash	Manikandan Rajendran	View Answer on Stackoverflow
Solution 5 - Bash	kenorb	View Answer on Stackoverflow
Solution 6 - Bash	HHHartmann	View Answer on Stackoverflow

How to give a pattern for new line in grep?

Bash Problem Overview

Bash Solutions

Solution 1 - Bash

Solution 2 - Bash

Solution 3 - Bash

Solution 4 - Bash

Solution 5 - Bash

Solution 6 - Bash

Further understanding setRetainInstance(true)

Is there a way to pass the DB user password into the command line tool mysqladmin?

Attributions