Do grep and cp treat "recursive" the same?

Your grep command,

grep -R "find me" *.php 

... contains a filename globbing pattern, *.php. This will be expanded by the shell before the shell executes grep, so the actual command at execution may look something like

grep -R "find me" file1.php file2.php inc.php 

... where inc.php happens to be a directory name.

The grep utility would then search the given files for the expression that you provided. For directories mentioned on the command line, it would search all files and subdirectories beneath the directory for files with contents matching the expression. This means you would have found a match in inc.php/subdir/README had that file contained the string find me.

In short: Process (search for matching lines within) each name given on the command line according to the given options (recursively).

The cp command works the same way with regards to recursive actions:

cp -r inc/* ~/mywork/ 

The shell would expand the above command to something like

cp -r inc/file1 inc/file2 inc/dir1 inc/dir2 /home/myself/mywork/ 

The cp utility would then, for each individually named file or directory, copy that file or directory recursively to the destination directory.

In short: Process (copy to destination) each name given on the command line according to the given options (recursively).

Additional notes:

• The support in grep for searching recursively is a non-standard extension.

• Filename globbing patterns that may expand to names starting with a dash should be handled with care to not be confused with command-line options. Your grep command is, therefore, more safely written as

  grep -R -- "find me" *.php 

  or as

  grep -R -e "find me" -- *.php 

  ... where -- delimits the options and their arguments from the non-option operands. Your cp command does not have that issue, as the globbing pattern is guaranteed to expand to something starting with the string inc/.