Mailinglist Archive: opensuse (888 mails)

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Re: [opensuse] bash test for empty dir

On Thu, 20 Jan 2011, David C. Rankin wrote:
I stumbled across a neat use of ls -A for testing for an empty dir that
thought I would pass on:


if [[ $(ls -A ${1}) ]]; then

And I'd prefer the more readable and portable

if test -n "$(ls -A "$1")"; then

or the even more portable

if test "$(ls -A "$1" | wc -l)" -gt 0; then

I'm not sure about the 'ls -A' though, so a

if test "$(ls -a "$1" | wc -l)" -gt 2; then

might be preferable, '-a' should be pretty portable.

BTW: one might want to unset LS_OPTIONS and have a look at PATH before
using just "ls" (and not /bin/ls).

I'm glad I usually use perl for scripting that should be portable (or
get's longer than a couple commands ;)

If anybody has a better way, let me know. Thanks.

On a related note: How to test for a directory having any direct
subdirectories? In a somewhat explicit form:

num_subdirs() {
for dir; do
nlinks=$(stat -c '%h' "$dir");
subdirs=$(( $nlinks - 2 ));
### printf "'%s' has %d subdirectories.\n" "$dir" "$subdirs";
echo "$subdirs";
test "$#" -eq 1 && return $subdirs;

HTH & have fun!

Mine had one where I think 4 machines were so intertwined that none
would boot unless 2 of the others were up. And nothing else would boot
till those were up.
You are trapped in a maze of twisty little NFS-maps, all different.
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