You can do it with parameter expansion with the `@P` operator like this:



 prompt="\u"; echo ${prompt@P}

As of Bash 4.4, you can use the `@P` operator in [Parameter expansion][1]:

>`${parameter@operator}` 
>The expansion is either a transformation of the value of parameter or information about parameter itself, depending on the value of operator. Each operator is a single letter:
>
>**`@P`** The expansion is a string that is the result of expanding the value of parameter as if it were a prompt 

Here's some of the common [special characters available to the PS1 command][2]:

> The following lists the special characters that can appear in the prompt variables PS0, PS1, PS2, and PS4
>
>**`\a`** A bell character 
**`\d`** The date, in "Weekday Month Date" format (e.g., "Tue May 26") 
**`\e`** An escape character 
**`\H`** The hostname 
**`\u`** The username of the current user 
**`\w`** The current working directory


**Further Reading**:

* [Bash Echo expanded PS1][5]
* [Bash 4.4 prompt escape for number of jobs currently running][3]
* [Bash How to use operator parameter expansion ${parameter@operator}?][4]

[1]: https://www.gnu.org/software/bash/manual/bashref.html#Shell-Parameter-Expansion
[2]: https://www.gnu.org/software/bash/manual/bashref.html#Controlling-the-Prompt
[3]: https://stackoverflow.com/q/53870897/1366033
[4]: https://stackoverflow.com/q/40732193/1366033
[5]: https://stackoverflow.com/q/3451993/1366033

I would like to see the output of the escaped special characters used in setting up `$PS1`. For example, placing `\u` in PS1 will output the username of the current user.

So in essence:

    omar @ ~ > echo -e '\u'

Expect:

    omar

Actual output:

    \u



How to echo in bash the backslash escaped special characters used in PS1?

This just has to do with how each of those different languages handle **variable expansion**.

[**cmd**][1]:&nbsp; `C:\> echo %USERPROFILE%`  
[**bash**][2]: `$ echo $USERPROFILE`  
[**ps**][3]:&nbsp;&nbsp;&nbsp;&nbsp; `PS> echo $env:USERPROFILE`

In windows cmd prompt, variables should be surrounded by `%` on either side  
Whereas Bash and PowerShell indicate a variables by prefixing with a `$`.  

Git Bash [gets all existing Windows environment variables at startup][4], while powershell tries to limit polluting the global namespace by including them under the `$env` object

[![Shell Comparison][5]][5]

If you want to confirm the shell has access to the environment variable, you can **list all variables**:

[**cmd**][6] *([docs][7])*:&nbsp; `C:\> SET`  
[**bash**][8] *([docs][9])*: `$ printenv`  
[**ps**][10] *([docs][11])*:&nbsp;&nbsp;&nbsp;&nbsp; `PS> Get-ChildItem env:`


  [1]: https://ss64.com/nt/syntax-variables.html
  [2]: https://ss64.com/bash/syntax-variables.html
  [3]: https://ss64.com/ps/syntax-variables.html
  [4]: https://stackoverflow.com/a/38385930/1366033
  [5]: https://i.stack.imgur.com/sH4kB.png
  [6]: https://stackoverflow.com/q/5327495/1366033
  [7]: https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/set_1
  [8]: https://askubuntu.com/q/275965/349745
  [9]: https://ss64.com/bash/printenv.html
  [10]: https://stackoverflow.com/q/39800481/1366033
  [11]: https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_environment_variables

I have the same issue like https://stackoverflow.com/questions/32186840/git-for-windows-doesnt-execute-my-bashrc-file and tried to make the same steps. But my Git Bash (2.5.0, 64bit on Windows 7, 64bit) doesn't know my `%USERPROFILE%`.

    pitgrap@xxx MINGW64 /
    $ pwd
    /
    
    pitgrap@xxx MINGW64 /
    $ cd ~
    bash: cd: /%USERPROFILE%: No such file or directory

If I run Git Bash as Administror, it works. :( 
But I don't want to run it everytime as Administrator. Any ideas?


Git for Windows doesn't know %USERPROFILE%

You need to use **`--no-anchored`** like this:

```bash
$ tar -xf ../mein.tar --wildcards --no-anchored "dir1/*.jpg"
```

According to the [man page][1]:

> ### File name matching options
>
> <pre><code>--anchored
> Patterns match file name start.
> 
> --no-anchored
> Patterns match after any / (default for exclusion).
> 
> --wildcards
> Use wildcards (default for exclusion).
> 
> --no-wildcards
> Verbatim string matching.
> </code></pre>


See also [untar only a certain number of files from a large tarball][2]


[1]: https://man7.org/linux/man-pages/man1/tar.1.html
[2]: https://unix.stackexchange.com/q/42198/128893

I have a tar file with the following contents:

```bash
$ tar tvf ../mein.tar 
drwxr-xr-x user/user         0 2019-01-14 15:31 ./
drwxr-xr-x user/user         0 2019-01-14 15:30 ./dir2/
-rw-r--r-- user/user         0 2019-01-14 15:30 ./dir2/file21.jpg
-rw-r--r-- user/user         0 2019-01-14 15:29 ./file1.jpg
drwxr-xr-x user/user         0 2019-01-14 15:30 ./dir1/
drwxr-xr-x user/user         0 2019-01-14 15:30 ./dir1/dir11/
-rw-r--r-- user/user         0 2019-01-14 15:30 ./dir1/dir11/file111.jpg
-rw-r--r-- user/user         0 2019-01-14 15:30 ./dir1/dir11/file112.jpg
drwxr-xr-x user/user         0 2019-01-14 15:30 ./dir1/dir21/
-rw-r--r-- user/user         0 2019-01-14 15:30 ./dir1/dir21/file122.jpg
-rw-r--r-- user/user         0 2019-01-14 15:30 ./dir1/dir21/file121.jpg
-rw-r--r-- user/user         0 2019-01-14 15:30 ./dir1/file11.jpg
```

It contains several sub-directories which may or may not contain jpg files. The file names are not always the same, but I know that there is exactly one jpg file in directory 'dir1'. I want to extract this file only, none of the other jpg files, neither in dir2 nor in dir1/dir*.



What I have tried so far is

```bash
$ tar -x -f ../mein.tar --wildcards 'dir1/*.jpg'
tar: dir1/*.jpg: Not found in archive
tar: Exiting with failure status due to previous errors
```

or

```bash
$ tar -x -f ../mein.tar --wildcards --wildcards-match-slash 'dir1/*.jpg'
tar: dir1/*.jpg: Not found in archive
tar: Exiting with failure status due to previous errors
```

If I use:

```bash
$ tar -x -f ../mein.tar --wildcards  "*.jpg"
```

Then I get all jpg files, this is not what I want.

Does anyone have a clue how to extract the jpg file in dir1 given that I don't know the exact name of that file? What I expect is to get exactly one file in sub-directory dir1, the output should be 'dir1/file11.jpg'.

