How do you pass a file or folder containing whitespace as an argument to a command-line program in a GNU/Linux or Cygwin environment?

There are occasions when you are working with files and folders that contain spaces in them. The problem is any time you try and pipe files / folders containing whitespace to another command-line program, the files / folders containing whitespace are interpreted as separate arguments rather than as a single argument. For example, consider the following directory tree:

Folder With Spaces
Folder With Spaces/FolderWithoutSpaces
Folder With Spaces/FolderWithoutSpaces/file with spaces.txt
FolderWithoutSpaces
FolderWithoutSpaces/fileWithoutSpaces.txt

If you try and run a shell command such as "grep 'some text' $(find . -type f)", you'll get the following output:

grep: ./Folder: No such file or directory
grep: With: No such file or directory
grep: Spaces/FolderWithoutSpaces/file: No such file or directory
grep: with: No such file or directory
grep: spaces.txt: No such file or directory

The big question is, how do you pipe files / folders that have whitespace in them as arguments to a command line program?

You would be better off using the -exec flag and quoting your arguments. Example:

find . -type f -exec grep stuff '{}' \;

The quotes will keep the spaces from being interpreted and you don't have to pipe everything through xargs unnecessarily.

From the manpage:

 -exec command ;
              Execute command; true if 0 status is returned.  All following arguments to find are taken to be arguments to the command until  an  argument
              consisting  of  `;'  is encountered.  The string `{}' is replaced by the current file name being processed everywhere it occurs in the argu‐
              ments to the command, not just in arguments where it is alone, as in some versions of find.  Both of these constructions might  need  to  be
              escaped  (with  a `\') or quoted to protect them from expansion by the shell.  See the EXAMPLES section for examples of the use of the -exec
              option.  The specified command is run once for each matched file.  The command is executed in the starting directory.   There  are  unavoid‐
              able security problems surrounding use of the -exec action; you should use the -execdir option instead.

Pipe in your arguments using xargs by delimiting your command line arguments in the preceding program with a null character passing the "-0" option to xargs, such as follows:

find . -type f -print0 | xargs -0 grep -l "some text"

This command will pass in any files / folders with whitespaces in them as single arguments rather than separate arguments.

Use the backslash character '\' preceeding the whitespace:

[randerson@localhost ~]$ mkdir Folder\ With\ Spaces
[randerson@localhost ~]$ ls | grep Folder\ With\ Spaces
Folder With Spaces
[randerson@localhost ~]$ 

Enclose the file names in (single or double) quotation marks:

$ mkdir "Folder With Spaces"
$ ls | grep "Folder With Spaces"
Folder With Spaces
$ ls | grep 'Folder With Spaces'
Folder With Spaces

The shell will expand variables inside double quotation marks:

$ FOO=With
$ ls | grep "Folder $FOO Spaces"
Folder With Spaces

You can also quote $(...) expansions if the result is a single filename:

$ ls -d "$(echo -n Folder With Spaces)"
Folder With Spaces

This will only work for single file names; for multiple files, use find -exec or xargs as suggested in the other answers.