I have a demo.txt file. I need to delete content in that file using a batch file. Please tell me the command to delete content for demo.txt file.
break>demo.txt
Try this.it will set an empty file on the place of demo.txt. As break is internal command that does nothing it should be pretty fast.Also the break command can produce output only with /? argument so this makes this method pretty robust.
Command Prompt:
break>c:\'file directory'\demo.txt
PowerShell:
Clear-Content c:\'file directory'\demo.txt
type nul > demo.txt
works and also works in JPSoft's TakeCommand TCC.EXE command shell (where "break" will output "BREAK is ON" rather than nothing as it does in Microsoft CMD.EXE)
The general idea is to find a command that outputs Nothing and redirect that to the file using >
This seems most intuitive to me:
copy /y nul demo.txt
NOTE: Unfortunately, like the other methods provided here, this fails if demo.txt is currently in use by another process. In such a case it is sometimes possible to open the file in a text editor and delete all the contents, even though the file is in use. I don't know of a way to do this from the command line.
If the file is used by another application command prompt redirection may fail (as it requires more file access then necessary). In that case you can use powershell:
PS> Set-Content file.txt $null
Note: do not expect that it will allow access to exclusively opened files.
Related
I have a text file with lots of commands in it and I want to sent those commands to a software called thermocal. It is a console application. I found the command below, but it doesn't work for me.
Do I need to put this .exe file in the same folder of the batch file to make it work or any thing else?
type somefile.txt | Thermocal.exe
Batch scripts can be considered as a collection of lines you could also type in a command line prompt one after another. With respect to this it might be helpful for you, to play with cmd in order to get a feeling for what is happening.
About starting thermocal: Assuming thermocal is not part of PATH then the batch file either needs to change the current directory to the one with termocal.exe. Alternatively you might be able to call thermocal.exe with adding a path like C:\ProgramFiles\Thermocal\thermocal.exe . Play with cmd to find out, what works and what doesn't
When you are able to start thermocal from the command line prompt window, you can start experimenting with the call. You will probably end of with something like this in your command line window:
C:\ProgramFiles\Thermocal> thermocal argument1 argument 2
If this works, you can start with batch programming :)
Assuming your arguments are stored in somefile.txt like this:
argument1 argument 2
TYPE does nothing more than printing a file:
TYPE somefile.txt
Now you need to use the result of the output as command line arguments:
for /f %%i in ('type somefile.txt') do (thermocal.exe %%i)
I ran a program on Windows 7 that was compiled under Cygwin and passed "NUL" as an output file name. Instead of suppressing output it actually created a file named "NUL" in the current directory. (Apparently it expects "/dev/null", even on Windows.) Now I'm stuck with this "NUL" file that I cannot delete!
I've already tried:
Windows Explorer - error: "Invalid MS-DOS function" (yes, that is seriously what it says!)
Command prompt using "del NUL" - error: "The filename, directory name, or volume
label syntax is incorrect."
Deleting the entire directory - same deal as just deleting the file
remove() in a C program - also fails
How can I get rid of these NUL files (I have several by now), short of installing the full Cygwin environment and compiling a C program under Cygwin to do it?
Open a command prompt and use these commands to first rename and then delete the NUL file:
C:\> rename \\.\C:\..\NUL. deletefile.txt
C:\> del deletefile.txt
Using the \\.\ prefix tells the high-level file I/O functions to pass the filename unparsed to the device driver - this way you can access otherwise invalid names.
Read this article about valid file / path names in Windows and the various reserved names.
If you have Git for Windows Installed (v2.18) do the following
Open the directory containing the files you want to remove
Left Click and select Git Bash Here
Type rm nul.json at the command prompt and hit ENTER, the file now should be removed.
NOTE: These screenshots show the removal of file nul.topo.json which is another file that I could not removed with a simple delete.
If you have git on windows, just right click on the folder containing the nul file -> go to gitbash here -> and type "rm nul" or "rm nul.json" depending upon the file type.
I had a similar issue. It was probably caused by Cygwin as well (since I use this regularly), but I've since forgotten exactly how the file was created.
I also had trouble deleting it. I followed the advice of some other posts and tried booting into safe mode to delete the file, though this did nothing. The tip from +xxbbcc didn't work for me either.
However, I was able to delete the file using the Cygwin terminal! Cygwin createth and Cygwin destroyeth.
To remove a nul file situated here:
C:\unix\cygwin\dev\nul
I simply use (tested only on Windows 10) :
Del \?\C:\unix\cygwin\dev\NUL
I solved this in a slightly different way.
I thought I would add this here because it is high in the google results and I had a similar issue for a folder named NUL.
I tried rmdir\\?\C:\My\Path\NUL and rmdir\\.\C:\My\Path\NUL without any success and also tried several commands using bash from my SourceTree installation. No joy.
In the end I used DIR /X /A from cmd to list the short names in the parent directory. This showed me NUL~1 for my NUL folder and identified the crux of the problem.
This was then used in the standard command rmdir /s NUL~1 and finally resolved the issue.
I was having this same issue.
If you have WSL2 installed just go to that directory and run:
rm -f nul
In my case the file was lowercase. You should be good.
Try writing a short C program that calls the Windows API to delete that file.
http://msdn.microsoft.com/en-us/library/aa363915%28v=vs.85%29.aspx
If that doesn't work, try opening a handle to the file with CreateFile() with FILE_FLAG_DELETE_ON_CLOSE, and then close the handle.
I have a Windows batch file which has an instruction to execute an EXE file in a location whose path contains accented characters. Following are the contents of the batch file.
#echo off
C:\español\jre\bin\java.exe -version
C:\español\jre\bin\java.exe - This path exists and is proper. I can run this command directly on cmd.exe. But when I run the command from a bat/cmd file it fails saying "The system cannot find the path specified"
One way to fix this is by setting code page to 1252 (that works for me). But I'm afraid we'd have to set code pages for any non-English locale and figuring out which code page to use is pretty difficult.
Is there an alternative approach to fix this problem? Maybe a command-line option or something else?
Another way of doing this, in Windows, is by using wordpad.exe:
Run wordpad.exe
Write your script as you usually do, with accents
Choose Save as > Other formats
Choose to save it as Text document MS-DOS (*.txt)
Change the file extension from .txt to .bat
I had the same problem, and this answer solved it. Basically you have to wrap your script with a bunch of commands to change your terminal codepage, and then to restore it.
#echo off
for /f "tokens=2 delims=:." %%x in ('chcp') do set cp=%%x
chcp 1252>nul
:: your stuff here ::
chcp %cp%>nul
Worked like a charm!
I'm using Notepad++ and it has an option to change "character sets", OEM-US did the trick. ;)
Since you have #echo off you can't see what your batch is sending to the command prompt. Reproducing your problem with that off it seems like the ñ character gets misinterpreted since the output I see is:
C:\espa±ol\jre\bin\java -version
The system cannot find the path specified.
I was able to get it to work by echoing the command into the batch file from the command prompt, i.e.
echo C:\español\jre\bin\java.exe -version>>test.bat
This seems to translate the character into whatever the command prompt is looking for, though I've only tested it with English locale set so I don't know if it'll work in all situations for you. Also, if you open the batch in a text editor like notepad it looks wrong (C:\espa¤ol\jre\bin\java.exe)
Use Alt + 0164 for ¤ instead of Alt + 164 ñ in a batch file... It will look odd, but your script should run.
You can use Visual Studio Code and it will let you select the encoding you want to use. Lower right corner, you select the encoding and will display option "save with encoding". Select DOS and will save the accented chars.
I also had the same problem. I was trying to create a simple XCOPY batch file to copy a spreadsheet from one folder to another. Its name had the "é" character in it, and it refused to copy.
Even trying to use Katalin's and Metalcoder's suggestions didn't work on my neolithic Windows XP machine. Then I suddenly thought: Why not keep things as simple as possible (as I am myself extremely simple-minded when it comes to computers) and just substitute, in the batch file code, "é" with the wildcard character "?".
And guess what? It worked!
I am just starting to get a handle on batch programming.
To date, I've been copy/pasting into the MS-DOS command prompt from a text editor. Some of these copy pastes are getting large. Im sure there is a better way to go about this, ie. writing a line in command prompt that calls other text files (effectively doing the work of copy pasting).
Are these external files going to be .bat (which are just text that could also be put directly into the command prompt?) or .txt or something else?
I am mainly looking into this so that I can get into reusing code and getting into looping.
Are there any tutorials someone would recommend to get my acquainted with these topics?
Thanks for any help.
You can name a text file .bat or .cmd (the latter if you know it's only usable as a Windows batch file) and put commands into it, line by line.
You can run such files by typing their name at the command prompt when you're in the directory where they reside (or if they are contained in one of the PATH directories).
By default the behavior will match pretty much exactly with what you would type by hand. You'll see what commands are executed as well as their output. For example the following batch file (saved as test.cmd here)
echo Hello World
dir /b *.cmd
yields the following output when run
> echo Hello World
Hello World
> dir /b *.cmd
date.cmd
foo.cmd
test.cmd
x.cmd
y.cmd
You can suppress the output of the command being run by including the line
echo off
in your batch file. Prefix it with an # to suppress command output for that line in particular, but ever subsequent command won't be echoed:
#echo off
If other concrete questions arise, feel free to ask.
I have tried prefixing lines with semicolons, 'REM', etc.. but no matter what when I run my batch file I keep getting "unknown command REM whatever"
"REM test" It is not recognized, and it is windows vista. I simply get "rem" output back to my console.
That's entirely normal behavior. Batch files are simply sequences of commands that are run one after another. So every line will get output to the console as if it were typed there.
H:\>echo rem test > test.cmd
H:\>test
yields the output
H:\>rem test
as if I typed rem test directly to the console.
You can suppress this by either prefixing the line with #:
#rem test
or by including echo off in the batch file:
#echo off
rem test
If I put ":: test" and execute it I get back "Test".
Can't reproduce here.
If I put "; test" it recursively executes itself
A semicolon at the start of the line seemingly gets ignored.
If you're talking about cmd.exe batch files under Windows, you can use:
rem this method or
:: this method.
For bash and a lot of other UNIX-type shells, you use:
# this method.
I'm pretty certain you're not using cmd.exe since that would give you an error like:
'rem' is not recognized as an internal or external command,
operable program or batch file.
rather then:
Unknown command ...
If you are using a UNIX-type shell, the # character is almost certainly what you're after. If you let us know exactly the shell you're using, we can probably help out further.
you probably created an UNICODE file. These files contain 2 bytes header named BOM
which is not shown by any editor but cmd attempts to execute them and fails.
To make sure this is indeed an issue: type any other command at the very beginning
of your file and see it throws the same error - for example #echo test
To fix it, just create a new plain text file and copy content of the original file there.
then remove the original file and replace it by the newly created one.
In my case the problems are line endings. Somehow Maven or the Jenkins pipeline running on a Linux machine changed the line endings from Windows style (CR LF) to Unix style (LF). Changing them back solves the issue for me.