BASH remove leading and trailing spaces in array

Question

I've got data coming from mysql and some values have leading or trailing spaces.

This is the code I have:

IFS=$':' res=(${vals//$'\t'/:}) 

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

is there a simple effective way to ensure there are no leading or trailing space in res[i] ?

Thanks

EDIT This is the result of my MYSQL query before it goes through IFS.

ZnbMF0 9RrO7 1 SiteA password password 12 1234 1234 456 456 0 0 0 0 0 0 0 0 [email protected] test user 5 2222 0 0 0 0 server address 0 0 [email protected] 0 0 0 0 0 0 0 0 0 0 0 0 0 NULL

In MySQL the email addresses have leading and trailing spaces. Processing through IFS and then Looping though it as :

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

Results in:

0: ZnbMFO*
1: 9RrO7*
2: 1*
3: SiteA*
4: password*
5: password*
6: 12*
7: 1234*
8: 1234*
9: 456*
10: 456*
11: 0*
12: 0*
13: 0*
14: 0*
15: 0 *
16: 0*
17: 0*
18: 0*
19: [email protected] *
20: test*
21: user*
22:  5*
23:  2222 *
24: 0*
25: 0 *
26: 0*
27: 0*
28: server*
29: address*
30: 0*
31: 0*
32:  [email protected] *
33: 0*
34: 0*
35: 0*
36: 0*
37: 0*
38: 0*
39: 0 *
40: 0*
41:  0*
42: 0*
43: 0 *
44: 0*
45: 0*
46: NULL*

The * is there just to highlight the trailing space.

Thanks

Do you want to remove the spaces in your array or just leave them out in the output? — Cyrus
– Cyrus, Commented Apr 7, 2020 at 14:13
What does the input look like? You're replacing tabs with colons and then split the string on colons, any reason you don't split on tabs directly? What does the desired output look like? — Benjamin W.
– Benjamin W., Commented Apr 7, 2020 at 14:21
Please, if you want us to help you, post an example of the input you have (produced by mysql) and the corresponding output you want to get. — Pierre François
– Pierre François, Commented Apr 7, 2020 at 14:38
@Cyrus ideally I'd like to remove then from the array. Thanks I'll try to get some sample data to show what happens. — Rocket
– Rocket, Commented Apr 7, 2020 at 15:12

anubhava · Accepted Answer · 2020-07-28 10:49:32Z

5

Let's say you have an array as this one:

arr=('foo bar' '[email protected] ' \
' [email protected] ' '    [email protected]         ')

To check array content using printf:

printf '[%s]\n' "${arr[@]}"

This will show:

[foo bar]
[[email protected] ]
[ [email protected] ]
[    [email protected]         ]

Now for leading and trailing space removal:

shopt -s extglob                     # turn on extended glob
arr=( "${arr[@]/#+([[:blank:]])/}" ) # remove leading space/tab from each element
arr=( "${arr[@]/%+([[:blank:]])/}" ) # remove trailing space/tab from each element

Now if you print array again:

printf '[%s]\n' "${arr[@]}"

It will show:

[foo bar]
[[email protected]]
[[email protected]]
[[email protected]]

edited Jul 28, 2020 at 10:49

answered Apr 7, 2020 at 19:23

anubhava

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3 Comments

Rocket Over a year ago

Thanks this seems to do exactly what I was looking for :)

akshay Over a year ago

This solution removes only one whitespace from the beginning and the end. It doesn't remove all leading and trailing whitespaces. Check with input= arr=(' foo bar ')

anubhava Over a year ago

Good point @akshay. I have edited answer to take care of multiple leading and trailing whitespaces.

Quasímodo · Accepted Answer · 2020-04-07 14:31:05Z

0

Not sure if you would call it simple, but you can use sed:

echo "${res[i]}" | sed 's/^ *\| *$//g'

vals=$' a \t c d'
IFS=$':' res=(${vals//$'\t'/:})

for (( i=0 ; i<${#res[@]} ; i++ )); do
    echo X${res[i]}X
    res[$i]=$(echo "${res[i]}" | sed 's/^ *\| *$//g')
    echo X${res[i]}X
done

Output:

X a X
XaX
X c dX
Xc dX

edited Apr 7, 2020 at 14:31

answered Apr 7, 2020 at 14:06

Quasímodo

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