List all files/dirs in or below the current directory that match 'filename'.
What is the Linux equivalent of DOS dir /s /b filename?
ls
The direct equivalent isfind . -iname <filename>which will list all files and directories called <filename> in the current directory and any subdirectories, ignoring case.If your version of find doesn't support -iname, you can use -name instead.  Note that unlike -iname, -name is case sensitive.If you only want to list files called <filename>, and not directories, add -type ffind . -iname <filename> -type fIf you want to use wildcards, you need to put quotes around it, e.g.find . -iname *.txt -type fotherwise the shell will expand it.As others have pointed out, you can also do:find . | grep \.txt$grep will print lines based on regular expressions, which are more powerful than wildcards, but have a different syntax.See man find and man grep for more details.