I want to get a list of files and then read the results into an array where each array element corresponds to a file name. Is this possible?
asked Jun 11, 2012 at 13:50
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1Yes, it is possible. Maybe not advisable if the names might contain arbitrary characters (spaces and newlines in the names cause grief), but it is doable. Which bit of the manual did you have difficulty understanding?– Jonathan LefflerCommented Jun 11, 2012 at 13:53
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How is the list being defined? bash has arrays, but depending on how the list is generated, different techniquest are better than others. In any case, post also your own attempts to solve the problem.– user1934428Commented Oct 26, 2021 at 11:57
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6 Answers
Don't use ls, it's not intended for this purpose. Use globbing.
shopt -s nullglob
array=(*)
array2=(file*)
array3=(dir/*)
The nullglob option causes the array to be empty if there are no matches.
answered Jun 11, 2012 at 13:53
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Thanks, Is there anyway I can pipe the results of these? I tried something like arr(* | grep ".txt") but it does not like it. Commented Jun 11, 2012 at 14:00
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11@dublintech: You don't need
grep, just include the string in your glob:array=(*.txt)orarray=(*foo*)Commented Jun 11, 2012 at 14:02 -
1You can also append filenames to an array, output filenames and loop through them.– vhsCommented Aug 4, 2018 at 6:08
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To my pleasant surprise, this also works with filenames that have whitespace or special characters in them! Tested with GNU bash, version 5.0.– famzahCommented Jan 2, 2023 at 10:04
Following will create an array arr with ls output in current directory:
arr=( $(ls) )
Though using output of ls is not safe at all.
Much better and safer than ls you can use echo *:
arr=( * )
echo ${#arr[@]} # will echo number of elements in array
echo "${arr[@]}" # will dump all elements of the array
answered Jun 11, 2012 at 13:53
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11
lsis not necessary and should not be used for this purpose. Commented Jun 11, 2012 at 13:54 -
Agreed, I just wanted to tell how to create an array from some command output. However I edited my answer to stress that
lsoutput should be avoided.– anubhavaCommented Jun 11, 2012 at 13:56 -
3When the array expansion is not quoted, all elements of the array are represented as a string, rather than individual elements of the array. Unquoted
${arr[*]}and${arr[@]}are the same.– jordanmCommented Jun 11, 2012 at 16:19 -
1Does anyone knows what is the max number of filenames / elements an array can hold?– dat789Commented Mar 31, 2016 at 9:16
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3anubhava, please remove your
arr=( $(ls) )line. Or if you want to leave it, please explicitly add a mention like don't do this, it's broken. Commented Apr 1, 2018 at 12:09
In bash you can create an array of filenames with pathname expansion (globbing) like so:
#!/bin/bash
SOURCE_DIR=path/to/source
files=(
"$SOURCE_DIR"/*.tar.gz
"$SOURCE_DIR"/*.tgz
"$SOURCE_DIR"/**/*
)
The above will create an array called files and add to it N array elements, where each element in the array corresponds to an item in SOURCE_DIR ending in .tar.gz or .tgz, or any item in a subdirectory thereof with subdirectory recursion possible as Dennis points out in the comments.
You can then use printf to see the contents of the array including paths:
printf '%s\n' "${files[@]}" # i.e. path/to/source/filename.tar.gz
Or using parameter substitution to exclude the pathnames:
printf '%s\n' "${files[@]##*/}" # i.e. filename.tgz
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1You need to have
shopt -s globstarin order to use recursive globbing (**). Commented Aug 4, 2018 at 11:46 -
Not for me. And the default Bash on MacOS is 3.2 which does not have
globstar. What does counting the characters in some directory names withecho /usr/**/ | wc -coutput for you? On my Mac, in Sierra with Bash 3.2 or in Bash 4.4 withglobstaroff, it outputs 122. If I run Bash 4.4 withglobstaron, I get 277904. The latter is clearly recursive and the former is not. BTW,shoptis defined, but I presume you meanglobstar(in Bash 3.2,shopt -p globstargives an error, in Bash 4.4 it shows whether it's set or unset). Commented Aug 4, 2018 at 13:09 -
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hashonly works with external executables (tryhash -t lsandhelp hash) and isn't going to show anything forshoptbecause it's a builtin or forglobstarbecause it's an option rather than an executable. Trytype -a shoptto show whereshoptis coming from andshoptby itself to show the settings of all your options. Useecho "$BASH_VERSION"to show the version of your currently running shell (if it's Bash) and look at the output ofps -o tty,commandto see if it's actually/bin/bash. Comparefind /usr -type d | wc -landecho /usr/**/ | tr -cd " " | wc -c... Commented Aug 5, 2018 at 12:36 -
... the counts should be fairly close if recursive globbing is working. My counts are in the neighborhood of 3800. Commented Aug 5, 2018 at 12:36
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1I'm ok with leaving it here. It's not specific to the OP's question, but it's a useful technique when outputting file names/paths. Commented Aug 5, 2018 at 17:40
Actually, ls isn't the way to go. Try this:
declare -a FILELIST
for f in *; do
#FILELIST[length_of_FILELIST + 1]=filename
FILELIST[${#FILELIST[@]}+1]=$(echo "$f");
done
To get a filename from the array use:
echo ${FILELIST[x]}
To get n filenames from the array starting from x use:
echo ${FILELIST[@]:x:n}
For a great tutorial on bash arrays, see: http://www.thegeekstuff.com/2010/06/bash-array-tutorial/
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2You should iterate over the file glob OR create an array using a file glob as in my answer - not both!. When adding elements to an array, there's no reason to use the length of the array in a complex index expression (it won't work as expected if the array is sparse, for one thing).
array+=(element). There's no reason to use$(echo "$f")just do the assignment directly. There's a missing closing curly brace on one of yourechostatements. Commented Sep 30, 2013 at 14:17 -
2are you aware that what you're doing is a broken way to just do
FILELIST = ( * )? (or, ratherFILELIST += ( * )). Why on earth do you use$(echo "$f")instead of just"$f"? Commented Apr 1, 2018 at 12:12
Try this,
path="" # could set to any absolute path
declare -a array=( "${path}"/* )
I'm assuming you'll pull out the unwanted stuff from the list later.
If you need a more specific file listing that cannot be returned through globbing, then you can use process substitution for the find command with a while loop delimited with null characters.
Example:
files=()
while IFS= read -r -d $'\0' f; do
files+=("$f")
done < <(find . -type f -name '*.dat' -size +1G -print0)
