I am trying to batch rename files in a folder. For example, right now I want to remove the character at the second index in the names of all of the files in a given folder. I have written a Java program that will do this given the path of the file.
The problem is that I am trying to batch the process with PowerShell, and I have very little knowledge of PowerShell. I basically just started using it today, and mainly to test run my Java program from the command line. I decided to try PowerShell for this because I saw a YouTube video where someone used PowerShell recursively to remove a certain character (like a "-") from every spot it appears in every file name in a folder. I thought maybe I could recurse with PowerShell to batch the process of changing every file name.
I want to recursively call the Java program with PowerShell and have PowerShell pass in each path of each file one by one in a folder to the Java program. I don't know if this is possible, but I'm hoping it is.
I have tried the following, though since I don't really any knowledge of PowerShell, I don't really know what to try. "Copy" is the name of the folder in which the files I want to modify are located.
get-childitem -recurse | java -cp "C:\Users\Media PC\Documents\Renamer\src\main\java" org.example.Main $_.name
I am getting the Java program to run, because I'm getting an error back from the program saying I didn't pass in a proper file path.
Building on Abraham Zinala's helpful comment:
Leaving aside the fact that invoking an external program (i.e., creation of a child process) file by file is inefficient:
Get-ChildItem -File -Recurse | ForEach-Object {
java -cp "C:\Users\Media PC\Documents\Renamer\src\main\java" org.example.Main $_.FullName
}
Note: The -File switch limits results to just files (doesn't include directories).
PowerShell's automatic $_ variable can only be used inside script blocks ({ ... }), so using $_.name as an argument as-is won't work.
See this answer for all contexts in which $_ is meaningfully defined.
In order to pass an argument to a command that isn't designed to take its input directly from the pipeline, use the ForEach-Object cmdlet for custom-processing of each input object one at a time.
Inside the script block passed to it, you can use $_ to refer to the pipeline input object at hand.
Get-ChildItem outputs instances of the following .NET types:
System.IO.DirectoryInfo(for directories) and
System.IO.FileInfo (for files)
Their .FullName property contains their full, file-system-native path, so $_.FullName is a robust way to refer to just that. Given that .Name only reports the mere file name, it wouldn't be sufficient to identify the file at hand in a recursive traversal of the current dir.
In PowerShell (Core) 7+, you could use just $_, because there such instances consistently stringify as the value of their .FullName property (when passing arguments to an external program, objects are implicitly stringified) - unfortunately, this is not the case in Windows PowerShell; see this answer.
I am making an NW.js app on macOS, and want to run the app in dev mode
by double-clicking on an icon.
In the first step, I'm trying to make my shell script work.
Using VS Code on Windows (I wanted to gain time), I have created a run-nw file at the root of my project, containing this:
#!/bin/bash
cd "src"
npm install
cd ..
./tools/nwjs-sdk-v0.17.3-osx-x64/nwjs.app/Contents/MacOS/nwjs "src" &
but I get this output:
$ sh ./run-nw
: command not found
: No such file or directory
: command not found
: No such file or directory
Usage: npm <command>
where <command> is one of: (snip commands list)
(snip npm help)
npm#3.10.3 /usr/local/lib/node_modules/npm
: command not found
: No such file or directory
: command not found
Some things I don't understand.
It seems that it takes empty lines as commands.
In my editor (VS Code) I have tried to replace \r\n with \n
(in case the \r creates problems) but it changes nothing.
It seems that it doesn't find the folders
(with or without the dirname instruction),
or maybe it doesn't know about the cd command ?
It seems that it doesn't understand the install argument to npm.
The part that really weirds me out, is that it still runs the app
(if I did an npm install manually)...
Not able to make it work properly, and suspecting something weird with
the file itself, I created a new one directly on the Mac, using vim this time.
I entered the exact same instructions, and... now it works without any
issues.
A diff on the two files reveals exactly zero difference.
What can be the difference? What can make the first script not work? How can I find out?
Update
Following the accepted answer's recommendations, after the wrong line
endings came back, I checked multiple things.
It turns out that since I copied my ~/.gitconfig from my Windows
machine, I had autocrlf=true, so every time I modified the bash
file under Windows, it re-set the line endings to \r\n.
So, in addition to running dos2unix (which you will have to
install using Homebrew on a Mac), if you're using Git, check your
.gitconfig file.
Yes. Bash scripts are sensitive to line-endings, both in the script itself and in data it processes. They should have Unix-style line-endings, i.e., each line is terminated with a Line Feed character (decimal 10, hex 0A in ASCII).
DOS/Windows line endings in the script
With Windows or DOS-style line endings , each line is terminated with a Carriage Return followed by a Line Feed character. You can see this otherwise invisible character in the output of cat -v yourfile:
$ cat -v yourfile
#!/bin/bash^M
^M
cd "src"^M
npm install^M
^M
cd ..^M
./tools/nwjs-sdk-v0.17.3-osx-x64/nwjs.app/Contents/MacOS/nwjs "src" &^M
In this case, the carriage return (^M in caret notation or \r in C escape notation) is not treated as whitespace. Bash interprets the first line after the shebang (consisting of a single carriage return character) as the name of a command/program to run.
Since there is no command named ^M, it prints : command not found
Since there is no directory named "src"^M (or src^M), it prints : No such file or directory
It passes install^M instead of install as an argument to npm which causes npm to complain.
DOS/Windows line endings in input data
Like above, if you have an input file with carriage returns:
hello^M
world^M
then it will look completely normal in editors and when writing it to screen, but tools may produce strange results. For example, grep will fail to find lines that are obviously there:
$ grep 'hello$' file.txt || grep -x "hello" file.txt
(no match because the line actually ends in ^M)
Appended text will instead overwrite the line because the carriage returns moves the cursor to the start of the line:
$ sed -e 's/$/!/' file.txt
!ello
!orld
String comparison will seem to fail, even though strings appear to be the same when writing to screen:
$ a="hello"; read b < file.txt
$ if [[ "$a" = "$b" ]]
then echo "Variables are equal."
else echo "Sorry, $a is not equal to $b"
fi
Sorry, hello is not equal to hello
Solutions
The solution is to convert the file to use Unix-style line endings. There are a number of ways this can be accomplished:
This can be done using the dos2unix program:
dos2unix filename
Open the file in a capable text editor (Sublime, Notepad++, not Notepad) and configure it to save files with Unix line endings, e.g., with Vim, run the following command before (re)saving:
:set fileformat=unix
If you have a version of the sed utility that supports the -i or --in-place option, e.g., GNU sed, you could run the following command to strip trailing carriage returns:
sed -i 's/\r$//' filename
With other versions of sed, you could use output redirection to write to a new file. Be sure to use a different filename for the redirection target (it can be renamed later).
sed 's/\r$//' filename > filename.unix
Similarly, the tr translation filter can be used to delete unwanted characters from its input:
tr -d '\r' <filename >filename.unix
Cygwin Bash
With the Bash port for Cygwin, there’s a custom igncr option that can be set to ignore the Carriage Return in line endings (presumably because many of its users use native Windows programs to edit their text files).
This can be enabled for the current shell by running set -o igncr.
Setting this option applies only to the current shell process so it can be useful when sourcing files with extraneous carriage returns. If you regularly encounter shell scripts with DOS line endings and want this option to be set permanently, you could set an environment variable called SHELLOPTS (all capital letters) to include igncr. This environment variable is used by Bash to set shell options when it starts (before reading any startup files).
Useful utilities
The file utility is useful for quickly seeing which line endings are used in a text file. Here’s what it prints for for each file type:
Unix line endings: Bourne-Again shell script, ASCII text executable
Mac line endings: Bourne-Again shell script, ASCII text executable, with CR line terminators
DOS line endings: Bourne-Again shell script, ASCII text executable, with CRLF line terminators
The GNU version of the cat utility has a -v, --show-nonprinting option that displays non-printing characters.
The dos2unix utility is specifically written for converting text files between Unix, Mac and DOS line endings.
Useful links
Wikipedia has an excellent article covering the many different ways of marking the end of a line of text, the history of such encodings and how newlines are treated in different operating systems, programming languages and Internet protocols (e.g., FTP).
Files with classic Mac OS line endings
With Classic Mac OS (pre-OS X), each line was terminated with a Carriage Return (decimal 13, hex 0D in ASCII). If a script file was saved with such line endings, Bash would only see one long line like so:
#!/bin/bash^M^Mcd "src"^Mnpm install^M^Mcd ..^M./tools/nwjs-sdk-v0.17.3-osx-x64/nwjs.app/Contents/MacOS/nwjs "src" &^M
Since this single long line begins with an octothorpe (#), Bash treats the line (and the whole file) as a single comment.
Note: In 2001, Apple launched Mac OS X which was based on the BSD-derived NeXTSTEP operating system. As a result, OS X also uses Unix-style LF-only line endings and since then, text files terminated with a CR have become extremely rare. Nevertheless, I think it’s worthwhile to show how Bash would attempt to interpret such files.
On JetBrains products (PyCharm, PHPStorm, IDEA, etc.), you'll need to click on CRLF/LF to toggle between the two types of line separators (\r\n and \n).
I was trying to startup my docker container from Windows and got this:
Bash script and /bin/bash^M: bad interpreter: No such file or directory
I was using git bash and the problem was about the git config, then I just did the steps below and it worked. It will configure Git to not convert line endings on checkout:
git config --global core.autocrlf input
delete your local repository
clone it again.
Many thanks to Jason Harmon in this link:
https://forums.docker.com/t/error-while-running-docker-code-in-powershell/34059/6
Before that, I tried this, that didn't works:
dos2unix scriptname.sh
sed -i -e 's/\r$//' scriptname.sh
sed -i -e 's/^M$//' scriptname.sh
If you're using the read command to read from a file (or pipe) that is (or might be) in DOS/Windows format, you can take advantage of the fact that read will trim whitespace from the beginning and ends of lines. If you tell it that carriage returns are whitespace (by adding them to the IFS variable), it'll trim them from the ends of lines.
In bash (or zsh or ksh), that means you'd replace this standard idiom:
IFS= read -r somevar # This will not trim CR
with this:
IFS=$'\r' read -r somevar # This *will* trim CR
(Note: the -r option isn't related to this, it's just usually a good idea to avoid mangling backslashes.)
If you're not using the IFS= prefix (e.g. because you want to split the data into fields), then you'd replace this:
read -r field1 field2 ... # This will not trim CR
with this:
IFS=$' \t\n\r' read -r field1 field2 ... # This *will* trim CR
If you're using a shell that doesn't support the $'...' quoting mode (e.g. dash, the default /bin/sh on some Linux distros), or your script even might be run with such a shell, then you need to get a little more complex:
cr="$(printf '\r')"
IFS="$cr" read -r somevar # Read trimming *only* CR
IFS="$IFS$cr" read -r field1 field2 ... # Read trimming CR and whitespace, and splitting fields
Note that normally, when you change IFS, you should put it back to normal as soon as possible to avoid weird side effects; but in all these cases, it's a prefix to the read command, so it only affects that one command and doesn't have to be reset afterward.
Coming from a duplicate, if the problem is that you have files whose names contain ^M at the end, you can rename them with
for f in *$'\r'; do
mv "$f" "${f%$'\r'}"
done
You properly want to fix whatever caused these files to have broken names in the first place (probably a script which created them should be dos2unixed and then rerun?) but sometimes this is not feasible.
The $'\r' syntax is Bash-specific; if you have a different shell, maybe you need to use some other notation. Perhaps see also Difference between sh and bash
Since VS Code is being used, we can see CRLF or LF in the bottom right depending on what's being used and if we click on it we can change between them (LF is being used in below example):
We can also use the "Change End of Line Sequence" command from the command pallet. Whatever's easier to remember since they're functionally the same.
One more way to get rid of the unwanted CR ('\r') character is to run the tr command, for example:
$ tr -d '\r' < dosScript.py > nixScript.py
I ran into this issue when I use git with WSL.
git has a feature where it changes the line-ending of files according to the OS you are using, on Windows it make sure the line endings are \r\n which is not compatible with Linux which uses only \n.
You can resolve this problem by adding a file name .gitattributes to your git root directory and add lines as following:
config/* text eol=lf
run.sh text eol=lf
In this example all files inside config directory will have only line-feed line ending and run.sh file as well.
For Notepad++ users, this can be solved by:
The simplest way on MAC / Linux - create a file using 'touch' command, open this file with VI or VIM editor, paste your code and save. This would automatically remove the windows characters.
If you are using a text editor like BBEdit you can do it at the status bar. There is a selection where you can switch.
For IntelliJ users, here is the solution for writing Linux script.
Use LF - Unix and masOS (\n)
Scripts may call each other.
An even better magic solution is to convert all scripts in the folder/subfolders:
find . -name "*.sh" -exec sed -i -e 's/\r$//' {} +
You can use dos2unix too but many servers do not have it installed by default.
For the sake of completeness, I'll point out another solution which can solve this problem permanently without the need to run dos2unix all the time:
sudo ln -s /bin/bash `printf 'bash\r'`
I'm trying to automate an arduous process but I've run into a wall that I can't seem to google my way around.
This is the process that I'm trying to automate
The batch file contains:
cd %~dp0
"%~dp0raindrop.exe" -g om -i %1 -o "%~dp1
PAUSE
What I'm trying to do: Stream in from a folder a bunch of '.sm' files and pass them one by one through the bat file creating a Folder for the outputted file created from the .bat process.
Explaining what these set of commands do would be great as I would prefer to create one more fit for my purpose. Which is bulk converting and sorting, so the output directory assuming thats handled in that batch file would need to be understood.
What i've tried at the moment its just running the .bat as is
%1 is window-batch-ese for 'the first parameter'. That makes some sense, I hope.
%0 is window-batch-ese for 'the batch file itself'. If you think about it now knowing what %1 means, this does make a little bit of sense: It's the '0th parameter' - the one to the left of the first parameter, which is the batch file itself.
%~letters0 is a way to tell windows; I want %0, but, I want you to modify it. There are many letters. d in particular means 'drive letter', and p means path.
Thus,
%~dp0 is windows-batch-ese for 'the full path (including drive letter) to the directory where the batch file currently executing lives.
%~dp1 is windows-batch-ese for 'take param 1 and turn it into an absolute path, then give me the directory that contains this argument.
Thus, you should now be able to recreate what this batch script does in pure java:
It runs the file raindrop.exe, by asking windows to run that by providing the full, absolute path to that executable, which is located in the same place the batch file is located.
It then passes 6 arguments to it:
-g
-om
-i
the first parameter
-o
if the first parameter resolves to a file, then that file, turned into an absolute path, and then the directory (i.e. if passing 'foo.txt', and that is in C:\example\whatever\foo.txt, the last arg is C:\example\whatever).
Use ProcessBuilder and you can recreate this feature fully.
NB: Your batch script is probably broken; it's missing a closing quote. Also, the fact that %1 is not quoted means that any files with spaces in it will also break this batch script. I assume you have no need to replicate these bugs in the java take on this.
NB: Run raindrop.exe with ProcessBuilder. Forget the bat file, you don't want to run that.
Hello again Stack Overflow!
I am currently working on a Java program that is essentially a digitized character sheet for a Dungeons and Dragons style adventure. I'm currently learning how to use IntelliJ IDEA, and while I haven't been able to figure out how to create a standalone executable .jar file, I have been able to find a workaround in the form of a .bat file that I have nicknamed rubberglove.bat (because if you can't open a jar, you use a...).
However, as in my previous post, I've run into a problem, as one of my new players uses a Mac, and since I don't know if it's possible to run rubberglove.bat in a non-Windows environment, I'll probably have to translate it into something MacOS can understand. However, I've never owned a Mac, so I'm not sure what the file extension even is, let alone what to put inside.
The contents of rubberglove.bat are shown below:
java -jar [program_name].jar
What would the Mac equivalent of this file and the commands inside? Thanks in advance for all your help!
Create a file called rubberglove (or rubberglove.sh, the file suffix is optional). And then set the execute bit. Something like
$ cat << EOF > rubberglove
#!/usr/bin/env bash
java -jar [program_name].jar
EOF
$ chmod +x rubberglove
$ ./rubberglove
Error: Unable to access jarfile [program_name].jar
Adjust "[program_name]" as needed.
I have a Java program that reads an image file (.jpg, .bmp, .png )) and creates indices on that file using a clustering algorithm. But the problem is that every time I have to explicitly give the name of that image file, which is to be indexed. What I want is a code that will automatically scan all images present in my Linux system and index them. I found it's possible by shell script but still not getting it.
From what I understand, you want to execute an *.sh script through a java program which in turn loops over some files in a folder?
Have you tried something like this:
public void runCmd() throws IOException, InterruptedException {
String cmd = "/home_dir/./my_shell_script.sh";
Runtime run = Runtime.getRuntime();
Process pr = run.exec(cmd);
pr.waitFor();
}
This only gives a rough idea what you need to do, but you get the gist
You can use find, and pipe its output to your program:
find \( -name "*.jpg" -or -name "*.png" \) -printf "%h/%f\n" | java YourProgram
and read the filenames, including paths, from stdin (assuming none of them contains a newline character).
For the whole filesystem, you would start from the root dir:
find / ...
A better solution, and not too hard to implement, would be, to search the files in a platform neutral manner from your program, and giving it only a starting path. Here is a good solution, you only need to apply a filter for the file types (jpg, png, bmp).