CODEWITHSUNDEEP
arraysbashunixscripting
abelenky
abelenky

Reputation: 64730

Bash array with spaces in elements

I'm trying to construct an array in bash of the filenames from my camera:

FILES=(2011-09-04 21.43.02.jpg
2011-09-05 10.23.14.jpg
2011-09-09 12.31.16.jpg
2011-09-11 08.43.12.jpg)

As you can see, there is a space in the middle of each filename.

I've tried wrapping each name in quotes, and escaping the space with a backslash, neither of which works.

When I try to access the array elements, it continues to treat the space as the element delimiter.

How can I properly capture the filenames with a space inside the name?

Upvotes: 201

Views: 200375

Answers (14)

Manabu Nakazawa
Manabu Nakazawa

Reputation: 2365

If the elements of FILES come from another file whose file names are line-separated like this:

2011-09-04 21.43.02.jpg
2011-09-05 10.23.14.jpg
2011-09-09 12.31.16.jpg
2011-09-11 08.43.12.jpg

then try this so that the whitespaces in the file names aren't regarded as delimiters:

while read -r line; do
    FILES+=("$line")
done < ./files.txt

If they come from another command, you need to rewrite the last line like this:

while read -r line; do
    FILES+=("$line")
done < <(./output-files.sh)

Upvotes: 2

ychz
ychz

Reputation: 571

For those who prefer set array in oneline mode, instead of using for loop

Changing IFS temporarily to new line could save you from escaping.

OLD_IFS="$IFS"
IFS=$'\n'

array=( $(ls *.jpg) )  #save the hassle to construct filename

IFS="$OLD_IFS"

Upvotes: 6

Alcamtar
Alcamtar

Reputation: 1582

This was already answered above, but that answer was a bit terse and the man page excerpt is a bit cryptic. I wanted to provide a fully worked example to demonstrate how this works in practice.

If not quoted, an array just expands to strings separated by spaces, so that

for file in ${FILES[@]}; do

expands to

for file in 2011-09-04 21.43.02.jpg 2011-09-05 10.23.14.jpg 2011-09-09 12.31.16.jpg 2011-09-11 08.43.12.jpg ; do

But if you quote the expansion, bash adds double quotes around each term, so that:

for file in "${FILES[@]}"; do

expands to

for file in "2011-09-04 21.43.02.jpg" "2011-09-05 10.23.14.jpg" "2011-09-09 12.31.16.jpg" "2011-09-11 08.43.12.jpg" ; do

The simple rule of thumb is to always use [@] instead of [*] and quote array expansions if you want spaces preserved.

To elaborate on this a little further, the man page in the other answer is explaining that if unquoted, $* an $@ behave the same way, but they are different when quoted. So, given

array=(a b c)

Then $* and $@ both expand to

a b c

and "$*" expands to

"a b c"

and "$@" expands to

"a" "b" "c"

Upvotes: 15

subham prasad
subham prasad

Reputation: 31

#! /bin/bash

renditions=(
"640x360    80k     60k"
"1280x720   320k    128k"
"1280x720   320k    128k"
)

for z in "${renditions[@]}"; do
    echo "$z"
    
done

OUTPUT

640x360 80k 60k

1280x720 320k 128k

1280x720 320k 128k

`

Upvotes: 3

Madan Sapkota
Madan Sapkota

Reputation: 26111

I used to reset the IFS value and rollback when done.

# backup IFS value
O_IFS=$IFS

# reset IFS value
IFS=""

FILES=(
"2011-09-04 21.43.02.jpg"
"2011-09-05 10.23.14.jpg"
"2011-09-09 12.31.16.jpg"
"2011-09-11 08.43.12.jpg"
)

for file in ${FILES[@]}; do
    echo ${file}
done

# rollback IFS value
IFS=${O_IFS}

Possible output from the loop:

2011-09-04 21.43.02.jpg

2011-09-05 10.23.14.jpg

2011-09-09 12.31.16.jpg

2011-09-11 08.43.12.jpg

Upvotes: -1

Mark Stosberg
Mark Stosberg

Reputation: 13411

If you aren't stuck on using bash, different handling of spaces in file names is one of the benefits of the fish shell. Consider a directory which contains two files: "a b.txt" and "b c.txt". Here's a reasonable guess at processing a list of files generated from another command with bash, but it fails due to spaces in file names you experienced:

# bash
$ for f in $(ls *.txt); { echo $f; }
a
b.txt
b
c.txt

With fish, the syntax is nearly identical, but the result is what you'd expect:

# fish
for f in (ls *.txt); echo $f; end
a b.txt
b c.txt

It works differently because fish splits the output of commands on newlines, not spaces.

If you have a case where you do want to split on spaces instead of newlines, fish has a very readable syntax for that:

for f in (ls *.txt | string split " "); echo $f; end

Upvotes: 0

Jonni2016aa
Jonni2016aa

Reputation: 154

If you had your array like this: #!/bin/bash

Unix[0]='Debian'
Unix[1]="Red Hat"
Unix[2]='Ubuntu'
Unix[3]='Suse'

for i in $(echo ${Unix[@]});
    do echo $i;
done

You would get:

Debian
Red
Hat
Ubuntu
Suse

I don't know why but the loop breaks down the spaces and puts them as an individual item, even you surround it with quotes.

To get around this, instead of calling the elements in the array, you call the indexes, which takes the full string thats wrapped in quotes. It must be wrapped in quotes!

#!/bin/bash

Unix[0]='Debian'
Unix[1]='Red Hat'
Unix[2]='Ubuntu'
Unix[3]='Suse'

for i in $(echo ${!Unix[@]});
    do echo ${Unix[$i]};
done

Then you'll get:

Debian
Red Hat
Ubuntu
Suse

Upvotes: 9

Javier Salas
Javier Salas

Reputation: 1188

Another solution is using a "while" loop instead a "for" loop:

index=0
while [ ${index} -lt ${#Array[@]} ]
  do
     echo ${Array[${index}]}
     index=$(( $index + 1 ))
  done

Upvotes: 0

TNT
TNT

Reputation: 3620

Not exactly an answer to the quoting/escaping problem of the original question but probably something that would actually have been more useful for the op:

unset FILES
for f in 2011-*.jpg; do FILES+=("$f"); done
echo "${FILES[@]}"

Where of course the expression would have to be adopted to the specific requirement (e.g. *.jpg for all or 2001-09-11*.jpg for only the pictures of a certain day).

Upvotes: 3

Dean Hall
Dean Hall

Reputation: 637

I agree with others that it's likely how you're accessing the elements that is the problem. Quoting the file names in the array assignment is correct:

FILES=(
  "2011-09-04 21.43.02.jpg"
  "2011-09-05 10.23.14.jpg"
  "2011-09-09 12.31.16.jpg"
  "2011-09-11 08.43.12.jpg"
)

for f in "${FILES[@]}"
do
  echo "$f"
done

Using double quotes around any array of the form "${FILES[@]}" splits the array into one word per array element. It doesn't do any word-splitting beyond that.

Using "${FILES[*]}" also has a special meaning, but it joins the array elements with the first character of $IFS, resulting in one word, which is probably not what you want.

Using a bare ${array[@]} or ${array[*]} subjects the result of that expansion to further word-splitting, so you'll end up with words split on spaces (and anything else in $IFS) instead of one word per array element.

Using a C-style for loop is also fine and avoids worrying about word-splitting if you're not clear on it:

for (( i = 0; i < ${#FILES[@]}; i++ ))
do
  echo "${FILES[$i]}"
done

Upvotes: 17

Khushneet
Khushneet

Reputation: 896

You need to use IFS to stop space as element delimiter.

FILES=("2011-09-04 21.43.02.jpg"
       "2011-09-05 10.23.14.jpg"
       "2011-09-09 12.31.16.jpg"
       "2011-09-11 08.43.12.jpg")
IFS=""
for jpg in ${FILES[*]}
do
    echo "${jpg}"
done

If you want to separate on basis of . then just do IFS="." Hope it helps you:)

Upvotes: 61

user123444555621
user123444555621

Reputation: 153234

There must be something wrong with the way you access the array's items. Here's how it's done:

for elem in "${files[@]}"
...

From the bash manpage:

Any element of an array may be referenced using ${name[subscript]}. ... If subscript is @ or *, the word expands to all members of name. These subscripts differ only when the word appears within double quotes. If the word is double-quoted, ${name[*]} expands to a single word with the value of each array member separated by the first character of the IFS special variable, and ${name[@]} expands each element of name to a separate word.

Of course, you should also use double quotes when accessing a single member

cp "${files[0]}" /tmp

Upvotes: 132

Dan Fego
Dan Fego

Reputation: 14034

I think the issue might be partly with how you're accessing the elements. If I do a simple for elem in $FILES, I experience the same issue as you. However, if I access the array through its indices, like so, it works if I add the elements either numerically or with escapes:

for ((i = 0; i < ${#FILES[@]}; i++))
do
    echo "${FILES[$i]}"
done

Any of these declarations of $FILES should work:

FILES=(2011-09-04\ 21.43.02.jpg
2011-09-05\ 10.23.14.jpg
2011-09-09\ 12.31.16.jpg
2011-09-11\ 08.43.12.jpg)

or

FILES=("2011-09-04 21.43.02.jpg"
"2011-09-05 10.23.14.jpg"
"2011-09-09 12.31.16.jpg"
"2011-09-11 08.43.12.jpg")

or

FILES[0]="2011-09-04 21.43.02.jpg"
FILES[1]="2011-09-05 10.23.14.jpg"
FILES[2]="2011-09-09 12.31.16.jpg"
FILES[3]="2011-09-11 08.43.12.jpg"

Upvotes: 168

Chris Seymour
Chris Seymour

Reputation: 85883

Escaping works.

#!/bin/bash

FILES=(2011-09-04\ 21.43.02.jpg
2011-09-05\ 10.23.14.jpg
2011-09-09\ 12.31.16.jpg
2011-09-11\ 08.43.12.jpg)

echo ${FILES[0]}
echo ${FILES[1]}
echo ${FILES[2]}
echo ${FILES[3]}

Output:

$ ./test.sh
2011-09-04 21.43.02.jpg
2011-09-05 10.23.14.jpg
2011-09-09 12.31.16.jpg
2011-09-11 08.43.12.jpg

Quoting the strings also produces the same output.

Upvotes: 2

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