In a directory size 80GB with approximately 700,000 files, there are some file names with non-English characters in the file name. Other than trawling through the file list laboriously is there:
man ascii (so I can test that these files are being identified)?Assuming that "foreign" means "not an ASCII character", then you can use find with a pattern to find all files not having printable ASCII characters in their names:
LC_ALL=C find . -name '*[! -~]*' (The space is the first printable character listed on http://www.asciitable.com/, ~ is the last.)
The hint for LC_ALL=C is required (actually, LC_CTYPE=C and LC_COLLATE=C), otherwise the character range is interpreted incorrectly. See also the manual page glob(7). Since LC_ALL=C causes find to interpret strings as ASCII, it will print multi-byte characters (such as π) as question marks. To fix this, pipe to some program (e.g. cat) or redirect to file.
Instead of specifying character ranges, [:print:] can also be used to select "printable characters". Be sure to set the C locale or you get quite (seemingly) arbitrary behavior.
Example:
$ touch $(printf '\u03c0') "$(printf 'x\ty')" $ ls -F dir/ foo foo.c xrestop-0.4/ xrestop-0.4.tar.gz π $ find -name '*[! -~]*' # this is broken (LC_COLLATE=en_US.UTF-8) ./x?y ./dir ./π ... (a lot more) ./foo.c $ LC_ALL=C find . -name '*[! -~]*' ./x?y ./?? $ LC_ALL=C find . -name '*[! -~]*' | cat ./x y ./π $ LC_ALL=C find . -name '*[![:print:]]*' | cat ./x y ./π 
LC_ALL=C instead of LC_COLLATE=C as it's doesn't make much sense to set LC_COLLATE to C without setting LC_CTYPE and to make sure it still works even when the LC_ALL variable is in the environment. SPC is printable, then what about TAB and LF which are also typically found in text files? LC_COLLATE and LC_CTYPE, see also the find(1) manpage. If you translate each file name using tr -d '[\200-\377]' and compare it with the original name, then any file names that have special characters will not be the same.
(The above assuming that you mean non-ASCII with foreign)
[ and ] in most tr implementations. [ and ] on my system. [ and ]s). thanks. You can use tr to delete any foreign character from a filename and compare the result with the original filename to see if it contained foreign characters.
find . -type f > filenames while read filename; do stripped="$(printf '%s\n' "$filename" | tr -d -C '[[:alnum:]][[:space:]][[:punct:]]')" test "$filename" = "$stripped" || printf '%s\n' "$filename"; done < filenames 
find output, use NUL-terminated output/input as shown in this answer. The accepted answer is helpful, but if your filenames are already in the encoding specified in LANG/LC_CTYPE, it's better to just do:
LC_COLLATE=C find . -name '*[! -~]*' Character classes are affected by LC_CTYPE, but the above command does not use character classes, only ranges, so LC_CTYPE just prevents the unusual characters from being replaced by question marks.
The other answers are usable, but the following gives better visual identification of the exact "offending" characters:
find | GREP_COLORS='mt=05;07;31' LC_ALL=C grep --color=always -E '[^[:print:]]' 
find | LC_ALL=C ack --color-match="blink reverse red" '[^[:print:]]' also works, if you have ack installed.