Shell – Add a newline into a filename with `mv`

command linenewlinesquotingshell

It's a serious question. I test some awk scripts and I need files with a newline in their names.

Is it possible to add a newline into a filename with mv?

I now, I can do this with touch:

touch "foo
bar"

With touch I added the newline character per copy and paste. But I can't write fooReturnbar in my shell.

How can I rename a file, to have a newline in the filename?

Edit 2015/06/28; 07:08 pm

To add a newline in zsh I can use, Alt+Return

Best Answer

It is a bad idea (to have strange characters in file names) but you could do

 mv somefile.txt "foo
 bar"

(you could also have done mv somefile.txt "$(printf "foo\nbar")" or mv somefile.txt foo$'\n'bar, etc... details are specific to your shell. I'm using zsh)

Read more about globbing, e.g. glob(7). Details could be shell-specific. But understand that /bin/mv is given (by your shell), via execve(2), an expanded array of arguments: argument expansion and globbing is the responsibility of the invoking shell.

And you could even code a tiny C program to do the same:

#include <stdio.h>
#include <stdlib.h>
int main() {
  if (rename ("somefile.txt", "foo\nbar")) {
     perror("rename somefile.txt");
     exit(EXIT_FAILURE);
  };
  return 0;
}

Save above program in foo.c , compile it with gcc -Wall foo.c -o foo then run ./foo

Likewise, you could code a similar script in Perl, Ruby, Python, Ocaml, etc....

But that is a bad idea. Avoid newlines in filenames (it will confuse the user, and it could break many scripts).

Actually, I even recommend to use only non-accentuated letters, digits, and +-/._% characters (with / being the directory separator) in file paths. "Hidden" files (starting with .) should be used with caution and parcimony. I believe using any kind of space in a file name is a mistake. Use an underscore instead (e.g. foo/bar_bee1.txt) or a minus (e.g. foo/bar-bee1.txt)

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