[SOLVED] How to redirect cat into script variable

sunnieside-up · 09-09-2011, 02:13 AM

Hi,

I have a question about linux scripting. I'm trying to put the contents of a file using cat into a variable, how do I do this? Thanks in advance.

EricTRA · 09-09-2011, 02:20 AM

Hello,

Assuming you are referring to Bash for scripting:

Code:

VARIABLE=$(cat yourfile)

If your question is more specific you need to provide more information. Are you for example only looking to put the entire contents in a variable or are you trying to create an array from a file? The more verbose your question, the more complete answers you'll get.

Kind regards,

Eric

colucix · 09-09-2011, 02:26 AM

You can also use redirection alone:

Code:

VARIABLE=$(<yourfile)

then use double quotes to embed the variable when you reference it, so that newlines are preserved:

Code:

echo "$VARIABLE"

salemeni · 09-09-2011, 02:27 AM

So you can do

Code:

VARIABLE=`cat yourfile`

java socket

MTK358 · 09-09-2011, 07:48 AM

Quote:

Originally Posted by salemeni

So you can do

Code:

VARIABLE=`cat yourfile`

Unlike $(command), backticks can be confused with single quotes and don't nest easily.

David the H. · 09-09-2011, 01:15 PM

What MTK358 said.

To populate an array from a file, there's a new (as of bash 4.0) mapfile built-in (a.k.a. readarray). Each line from stdin will be stored in a separate array element.

Code:

mapfile -t arrayname <file

The -t option removes the trailing newline from the entry, something you'll usually want to do.

For older shell versions you can use something like this:

Code:

while read line ; do
	arrayname+=( $line )
done <file

sunnieside-up · 09-09-2011, 02:49 PM

Yeah, I'm using bash, and these little things are a bit confusing to me at first, with what the spaces between equals signs counting and all that. Sweet, thanks for all the help!