bash scripting with echo, pipe, and variables

Question

I'd like to retrieve the result of a

echo $1/*.pem

and put the result in a array.

I tried:

a = echo $1/*.pem | grep pem  *

or

a = echo $1/*.pem

It fails.

When I do:

echo $1/*.pem

it display the good result

/opt/tmp/a.pem /opt/tmp/ab.pem

Possible duplicate of Bash: loop through all the files with a specific extension — Kind Stranger
– Kind Stranger, Commented Jun 26, 2017 at 17:18

MauricioRobayo · Accepted Answer · 2017-06-27 01:34:04Z

1

You can let bash do the expansion and use parenthesis to cast an array without the use of echo:

a=( "$1"/*.pem )
echo "${a[@]}"

You can use echo but you'll have to use command substitution to reassign the output of the echo command to the array, and you will have problems if you have spaces in the name of your path:

a=( $(echo $1/*.pem) )

edited Jun 27, 2017 at 1:34

answered Jun 26, 2017 at 17:13

MauricioRobayo

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4 Comments

Gordon Davisson Over a year ago

I'd also recommend double-quoting the array when you use it (e.g. echo "${a[@]}") -- again, this is to avoid problems with spaces or other shell metacharacters in the filenames. Double-quoting variable references is almost always a good idea in shell scripts.

MauricioRobayo Over a year ago

@GordonDavisson Thanks for the useful feedback, I have updated my answer with your recommendation.

aez Over a year ago

But a=( $(echo $1/*.pem) ) works retrieve only the first file in the directory

Gordon Davisson Over a year ago

@aez Both should work; make sure you're testing them correctly. For the first, the echo is a second command and must be on a separate line from the assignment (or at least separated with a semicolon, like this: a=( "$1"/*.pem ); echo "${a[@]}". Fir the second, make sure you use "${a[@]}" to get all elements of the array -- if you use $a, you only get the first element.

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