I have an hour variable in shell that contains UNIX time in seconds.
Then If want to format this hour, I use
date -u -d @$hour +"%Y-%m-%dT%H:%M:%S.000Z"
which works. However, I want to store the result of the above expression to another variable, so when I do:
formatted=$(( date -u -d @$hour +"%Y-%m-%dT%H:%M:%S.000Z" ))
it does not work. I do not know how will I reference the hour variable within an evaluation expression (whatever it is called).
The expression
formatted=$(( date -u -d @$hour +"%Y-%m-%dT%H:%M:%S.000Z" ))
use the $(( which works only for arithmetic. Change the double parentheses to single:
formatted=$( date -u -d @$hour +"%Y-%m-%dT%H:%M:%S.000Z" )
The latter works for strings.
For reference (these are POSIX shell features, not bash-specific):
$(($(Your syntax for command substitution is subtly wrong. The use of double parentheses after $ introduces a quite distinct context in Bash, which is known as arithmetic context.
So just drop one pair of parentheses.
formatted=$(date -u -d @$hour +"%Y-%m-%dT%H:%M:%S.000Z")
The use of backticks is syntactically valid, but discouraged.
formatted=`date -u -d @$hour +"%Y-%m-%dT%H:%M:%S.000Z"`
You can do it as following:
hour=1447409296 #Whatever timestamp value you want to set
formatted=`date -u -d @$hour +"%Y-%m-%dT%H:%M:%S.000Z"`
echo $formatted
or:
formatted=`date -u -d @$hour +"%Y-%m-%dT%H:%M:%S.000Z"`
