I am writing a shell script where I am setting few variables, whose value is the output of commands.
The errors I get are:
$ $tag_name="proddeploy-$(date +"%Y%m%d_%H%M")" -bash: =proddeploy-20141003_0500: command not found
now, I did read other similar questions and based on it, I tried various things:
spliting command into two calls
$ $deploy_date=date +"%Y%m%d_%H%M" bash: =date: command not found $ $tag_name="proddeploy-$deploy_date" bash: proddeploy- command not found
tried using backticks
$ $tag_name=`proddeploy-$(date +"%Y%m%d_%H%M")` bash: proddeploy-20141003_1734: command not found bash: =: command not found
tried using $()
$ $tag_name=$(proddeploy-$(date +"%Y%m%d_%H%M")) bash: proddeploy-20141003_1735: command not found bash: =: command not found
But in every case the command output is getting executed. how do I make it to stop executing command output and just store as a variable? I need this to work on ZSH and BASH.
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Answer
You define variables with var=string
or var=$(command)
.
So you have to remove the leading $
and any other signs around =
:
tag_name="proddeploy-$(date +"%Y%m%d_%H%M")" deploy_date=$(date +"%Y%m%d_%H%M") ^^ ^
From Command substitution:
The second form
`COMMAND`
is more or less obsolete for Bash, since it has some trouble with nesting (“inner” backticks need to be escaped) and escaping characters. Use$(COMMAND)
, it’s also POSIX!
Also, $()
allows you to nest, which may be handy.