Equivalent of "ls -t" ?

[Stan Brown]

I need to get a list of all the files in a given directory, sorted in
oldest -> newest into an array for processing.

What's a good way to do this?

 

[Brian McCauley]

I need to get a list of all the files in a given directory,

Use readdir (and its related functions).

sorted

See FAQ: How do I sort an array by (anything)?

oldest -> newest into an array for processing.

The function to get the age of a file is -M

What's a good way to do this?

To sort something (in this case filenames) according to some extrinsic
or computed property (in this case the age of the file with that name)
you can use the Schwartzian Transform (as per the FAQ).

<fish>

opendir my $dh, $dir or die $!;

my @files = map { $_->[0] }
sort { $b->[1] cmp $a->[1] }
map { [ $_, -M "$dir/$_" ] }
readdir $dh;

</fish>

--
\\ ( )
. _\\__[oo
.__/ \\ /\@
. l___\\
# ll l\\
###LL LL\\

 

[Anno Siegel]

I need to get a list of all the files in a given directory, sorted in
oldest -> newest into an array for processing.

What's a good way to do this?

Here is one:

my $dir = '.';
opendir my $d, $dir or die "bah $dir: $!";
my @l = sort { -M $a <=> -M $b } readdir( $d);
print join "\n", @l, '';

This is fine for small directories. For lots of files you may consider
a Schwartzian transform to reduce the overhead of "-M" calls. (See
"perldoc -q sort" for that.)

Anno

 

[Anno Siegel]

Stan Brown ([email protected]) wrote on MMMDCCXII September MCMXCIII in
<URL:\\ I need to get a list of all the files in a given directory, sorted in
\\ oldest -> newest into an array for processing.


ls -t orders them from newest to oldest. Anyway, here's a solution
(oldest to newest).

my $dir = ".";
opendir my $dh => $dir or die;
my @files = map {substr $_ => 8}
sort
map {sprintf "%08x$_" => (stat) [9], $_} grep {! /^\./} readdir $dh;

^^
That second "$_" seems to be a remnant of an earlier version. Otherwise,
it's a very true replication of "ls -tr", skipping files beginning with
"." and, cleverly, sorting alphabetically files that have the same mod-time.

Why the hex format?

Anno

 

[Stan Brown]

Stan Brown ([email protected]) wrote on MMMDCCXII September MCMXCIII in
<URL:\\ I need to get a list of all the files in a given directory, sorted in
\\ oldest -> newest into an array for processing.

ls -t orders them from newest to oldest. Anyway, here's a solution
(oldest to newest).

my $dir = ".";
opendir my $dh => $dir or die;
my @files = map {substr $_ => 8}
sort
map {sprintf "%08x$_" => (stat) [9], $_} grep {! /^\./} readdir $dh;
closedir $dh;

thanks for the help!

This works great in a small test program, but when I put this fragment in
to my bigger program (which is using "strict. I get the following run
time error:

Can't use string ("/usr/images/20031026") as a SCALAR ref while "strict
refs" in use at ./make_movie.pl line 474.

"/usr/images/20031026" is the directory I'm trying to get a list of files
from.

How can I fix this?

 

[Anno Siegel]

Stan Brown ([email protected]) wrote on MMMDCCXII September MCMXCIII in
<URL:\\ I need to get a list of all the files in a given directory, sorted in
\\ oldest -> newest into an array for processing.


ls -t orders them from newest to oldest. Anyway, here's a solution
(oldest to newest).

my $dir = ".";
opendir my $dh => $dir or die;
my @files = map {substr $_ => 8}
sort
map {sprintf "%08x$_" => (stat) [9], $_} grep {! /^\./} readdir $dh;

^^
That second "$_" seems to be a remnant of an earlier version. Otherwise,
it's a very true replication of "ls -tr", skipping files beginning with
"." and, cleverly, sorting alphabetically files that have the same mod-time.

Oh, but it fails for a file named "hundred%safe". Maybe the earlier version
was preferable

Why the hex format?

Anno

 

[Stan Brown]

Stan Brown ([email protected]) wrote on MMMDCCXII September MCMXCIII in
<URL:\\ I need to get a list of all the files in a given directory, sorted in
\\ oldest -> newest into an array for processing.

ls -t orders them from newest to oldest. Anyway, here's a solution
(oldest to newest).
my $dir = ".";
opendir my $dh => $dir or die;
my @files = map {substr $_ => 8}
sort
map {sprintf "%08x$_" => (stat) [9], $_} grep {! /^\./} readdir $dh;
closedir $dh;

thanks for the help!

This works great in a small test program, but when I put this fragment in
to my bigger program (which is using "strict. I get the following run
time error:

Can't use string ("/usr/images/20031026") as a SCALAR ref while "strict
refs" in use at ./make_movie.pl line 474.

"/usr/images/20031026" is the directory I'm trying to get a list of files
from.

How can I fix this?

It would help if I posted the line I bet :-(

opendir my $dh => $$::src_dir or die;

 

[Stan Brown]

ls -t orders them from newest to oldest. Anyway, here's a solution
(oldest to newest).
my $dir = ".";
opendir my $dh => $dir or die;
my @files = map {substr $_ => 8}
sort
map {sprintf "%08x$_" => (stat) [9], $_} grep {! /^\./} readdir $dh;
closedir $dh;

thanks for the help!
This works great in a small test program, but when I put this fragment in
to my bigger program (which is using "strict. I get the following run
time error:
Can't use string ("/usr/images/20031026") as a SCALAR ref while "strict
refs" in use at ./make_movie.pl line 474.
"/usr/images/20031026" is the directory I'm trying to get a list of files
from.
How can I fix this?

It would help if I posted the line I bet :-(

opendir my $dh => $$::src_dir or die;

Never mind!

Is there a rule that says you won't see your stupid typo, till you post it
for the world to see :-(

 

[Anno Siegel]

Anno Siegel ([email protected]) wrote on MMMDCCXII
September MCMXCIII in <URL:news:[email protected]>:

[] > sort
[] > map {sprintf "%08x$_" => (stat) [9], $_} grep {! /^\./}
readdir $dh;
[] ^^
[] That second "$_" seems to be a remnant of an earlier version. Otherwise,
[...]

There was no earlier version. The format was intended to be '%08x%s';
it's just that the directories I tested on didn't have files with %'s
in their names, so the typo remained unnoticed.

Yes. I noticed that the first $_ being in error was a more likely
scenario... after I posted.

[] Why the hex format?

Because I know timestamps are 32 bit integers, which are at most 8
hex digits. I contemplated figuring out how many digits I needed,
but then I realized that being lazy would save memory, so I used
hex digits instead of normal digits.

Right.

Anno