I have a file with a word written on it. I want my script to put that word in a variable.
How can I do that?
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5 Answers
in several of a million ways...
simplest is probably
my_var=$(cat my_file) If you use bash and you want to get spiffy you can use bash4's mapfile, which puts an entire file into an array variable, one line per cell
mapfile my_var < my_file 
3 Comments
Jonathan
newlines will make the first part try to execute and fail with a command not found error use var=$(cat file | tr -d '\n') to remove all new lines, including any trailing ones
wich
@Jonathan no it won't
bers
Be careful when using this with a single-line file. The resulting array variable will look like a normal one, but you won't be able to easily export it:
echo X > f; mapfile -t V < f; echo V is $V; export V; env | grep V=. Note how V is missing from env despite being defined before exporting.The simplest way is probably:
var=$(< file) which doesn't create a new process.
answered Jan 20, 2011 at 16:48
Diego Torres Milano
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5 Comments
Dennis Williamson
This works in Bash and other advanced shells, but not in the Bourne shell.
Amos Folarin
not cross platform... won't work in sh see stackoverflow.com/questions/7427262/…
David Tonhofer
Does anyone/anything even still use non-bash sh in 2018? Maybe Dick Tracy's watch??
neverMind9
Warning: no space prior to the “<” (i.e. “
(<” instead of “( <”).
Galigator
This solution does a transformation over 'endline' char on linux.
var="`cat /path/to/file`" This is the simple way. Be careful with newlines in the file.
var="`head -1 /path/to/file`" This will only get the first line and will never include a newline.
1 Comment
Student
I have a file nammed "log", and
$x="`cat log`" results in =2: command not foundI think the easiest way is something like
$ myvar=`cat file` 
1 Comment
Dennis Williamson
It's not necessary to export the variable and the spaces around the equal sign won't work.
I think it will strip newlines, but here it is anyway:
variable=$(cat filename) 
2 Comments
Dennis Williamson
It will only strip the final newline. If you seem to be getting the other newlines stripped, it's because you're not quoting the variable on output.
echo $variable vs. echo "$variable"
Tofandel
@DennisWilliamson Thanks for the hint, I was about to go crazy finding out why