bash: put output from `ls` into an array

samel_tvom · 07-25-2005, 06:54 PM

Hi!

I have a little script which puts the output from ls into an array.
However, it does not work if a file in the directory has a whitespace (or more) in its filename since my script will interpret that line from ls as two lines (or more depending on how many whitespaces their are)

my script (named array) looks like this:

#!/bin/bash
array=(`ls`)

len=${#array[*]}

i=0
while [ $i -lt $len ]; do
echo "$i: ${array[$i]}"
let i++
done

If I do an ls the result is:

[samel@arch bla]$ ls
array foobar

and the output from the script:

[samel@arch bla]$ ./array
0: array
1: foobar

BUT if I rename "foobar" to "foo bar"

the script gives:

[samel@arch bla]$ ./array
0: array
1: foo
2: bar

How should I solve this? I rather not use "ls | sed -ne numer" in a whileloop that puts line by line into the array, I only want to do ls once or so.

I actually intend to put the output from find, and if I do "a find" and it gives some hundreds line I don't want to repeat that every time in a whileloop since it takes a lot of time to get it finished.

Thanks a bunch!

Matir · 07-25-2005, 08:39 PM

Code:

IFS='
'

Then run it on find or ls -1.

This will cause it to ONLY split on newlines.

samel_tvom · 07-25-2005, 08:46 PM

thanks, that worked perfect!
what does
IFS='
'
do? what is IFS? some global variable of some sort?

Matir · 07-25-2005, 08:50 PM

IFS is the "Internal Field Separator". It's a character (or list of characters) that bash uses for filename globbing, etc. By putting the quotes a line apart, it includes just a newline. Despite what one would expect, IFS='\n' does NOT work.

slackbull · 07-25-2005, 09:31 PM

I ended up doing it like this

Code:

#!/bin/bash
IFS=!
ARRAY=(`find * -printf %f!`)
COUNT="0"

for i in ${ARRAY[*]}; do
    echo "$(($COUNT+1)): $i"
    let COUNT++;
done

Matir · 07-25-2005, 10:02 PM

Out of curiousity, what was your goal? If only to count files, why not just "find * | wc -l"?

samel_tvom · 07-26-2005, 09:23 AM

oh, the counting was not the thing. I just had len=${#array[*]} to make sure all of the "filenames from ls" got it's own index in the array, so if I had a directory with x files in it, echo $len would output x.

If I had a directory with x files, all with on whitespace in their names, the output from echo $len would be 2x and that's wrong. But now it's solved.

The reason why I want to use this with find, is that I wanted to improve my script that makes a playlist for mplayer. We all know how frustrating it is if you watch a TV-show and one episode is finished and you want to play the next.
With my script (the old one) you go into a directory and type
$playlist episode4.avi
and a playlist will be made from episode4.avi to the last file in the directory.

samel_tvom · 07-26-2005, 10:08 AM

my script now looks like this

#!/bin/bash
IFS='
'
types="*\.avi|*\.rm|*\.mpeg|*\.mpg|*\.mp3|*\.mp3"
playlist=(`find -name "*" | egrep -i "$types" | sort`)
length=${#playlist[*]}

if [ "x$1" != "x" ]; then
addtoplaylist=false;
else
addtoplaylist=true;
fi

touch playlist.playlist
for (( i=0 ; $i < $length ; i=$i+1 ))
do
line=${playlist[i]}
if [ "x`echo ${playlist[i]} | grep "$1"`" != "x" ]; then
addtoplaylist=true
fi
if [ "x$addtoplaylist" = "xtrue" ]; then
echo ${playlist[i]} >> playlist.playlist
fi

done

mplayer -fs -playlist playlist.playlist
rm playlist.playlist

it works fine for my purpose (that is going into a TV-show-episode-x directory since it usually only contains 22 files or so) but if I go into my music directory (I wouldn't really use this script to play my files because there are much better programs for that).
The thing that is taking time in the while-loop is

if [ "x`echo ${playlist[i]} | grep "$1"`" != "x" ]; then
addtoplaylist=true
fi

$1 is the argument you pass to the script. That argument is the file which I want to start to make the playlist from, so it is the file I first want to watch.
If I have
if [ "x${playlist[i]}" = "x$1" ]; then
addtoplaylist=true
fi

then I have to use ./ in my first argument:
$myscript ./episodeiwanttowatch.avi
beacuse all strings in ${playlist} starts with ./

is there another way to tell if $1 is a substring of ${playlist[i]}?

Thanks for your help btw, really appreciate it!

slackbull · 07-26-2005, 03:27 PM

Instead of greping, echoing, and setting addtoplaylist, here is some ways I'd do some things. Of course everyones different, and I'm not too familiar with any standards.

The first part just exits if theres no $1 instead of using and retesting addtoplaylist.

Then use the ${variable/search/replace} ThingeeMaBob (parameter substitution I think?) to strip the ./ off the $1 variable, and the $PLAYLIST array. It won't touch the variables if their is no ./ in them. That way you can use either formats. It's a builtin type deal so should be quick.

Then just send it through those test constructs and you should be good.

I didn't mess around with the IFS in there or anything, just wanted to give a few quick examples you can work with, if you like them.

Code:

#!/bin/bash -x

# Exit if no $1
: ${1?Need a parameter dude}

# Strips ./ off if its there, leaves it alone if it's not.
# Do it here instead of in the loop.
FILENAME=${1/\.\//}

# Get your array of filenames
PLAYLIST=(`find -name "*"`)

# Test constructs the same as if/then/else
for i in ${PLAYLIST[*]/\.\//}; do

    [ $FILENAME == $i ] && echo "Yeah, it matches"  || echo "No match"
    
done

twantrd · 07-26-2005, 05:41 PM

This is nice.

Quote:

[samel@arch bla]$ ./array
0: array
1: foobar

What if something outputted like:

Code:

0: array
1. foobar

Which file do you want to move? 
<user selects 1>

How would one perform some action on the number that is associated to the filename?

-twantrd

Matir · 07-26-2005, 08:16 PM

Or, a oneliner that should do the same thing.... matching $1 and building a playlist. I may be wrong on your intent, sorry.

Code:

#!/bin/bash
find . -name "$1*" | egrep '[\.mp3|\.mpeg|\.mpg|\.avi]$' > MYPLAYLIST

Alter extensions to suit taste.

twantrd · 07-26-2005, 10:43 PM

Thanks for the help matir but that wasn't what i wanted

. What i wanted was:

1. list files in a directory
2. prepend numbers to them
3. Prompt the user which file they want
4. Perform some command based on the input

So, for example...it would spit out:

Code:

1. file.txt
2. file1.txt
3. file2.txt

Which file do you pick?

So, the script will echo "Which file do you pick?" and wait for input. If the user inputs "1", an action will be performed on file.txt. Therefore, I don't know how to write the input that is associated with the filename piece. Thanks...

-twantrd

Matir · 07-26-2005, 10:55 PM

twantrd: sorry, my response was to the OP, not you (not that I mind helping you).

Using code from some of the early posts, just do something with "read ITEMNUM" and then access ${arrayname[$ITEMNUM]}

twantrd · 07-27-2005, 02:25 AM

Oh duh, I should've read up more about accessing elements in arrays. Thanks Matir!

-twantrd

samel_tvom · 07-28-2005, 02:26 PM

Thanks guys, I'll check out FILENAME=${1/\.\//}
and see if iy helps me, now I have an ugly hack,
if [ "x${playlist[i]}" = "x$1" -o "x${playlist[i]}" = "x./$1" ]; then ...
it works fine and it doesn't have to be more complicated.

now my script looks like this. It's really fast, it makes a playlist over 300 files in less than 1 second (compared to the 10 second with grepping echos...)

#!/bin/bash
IFS='
'
types="*\.avi|*\.rm|*\.mpeg|*\.mpg|*\.mp3|*\.mp3"
playlist=(`find -name "*" | egrep -i "$types" | sort`)
length=${#playlist[*]}

if [ "x$1" != "x" ]; then
addtoplaylist=false;
else
addtoplaylist=true;
fi

touch playlist.playlist
for (( i=0 ; $i < $length ; i=$i+1 ))
do
line=${playlist[i]}
if [ "x${playlist[i]}" = "x$1" -o "x${playlist[i]}" = "x./$1" ]; then
addtoplaylist=true
fi
if [ "x$addtoplaylist" = "xtrue" ]; then
echo ${playlist[i]} >> playlist.playlist
fi

done

mplayer -fs -playlist playlist.playlist
rm playlist.playlist

If you watch TV-series this script is nice. If you want all the files in a dir, you just don't pass an argument to the script.

have a good one!