Question

I have trying to run the below script to modify the timestamp in the Growl plist but the script is unable to update the plist.
If I execute the same thing from the command line then it works fine.

Please help.

#!/bin/sh
current=`date +"%Y-%m-%d %l:%M:%S +0000"`
cmd="defaults read com.Growl.GrowlHelperApp LastUpdateCheck -date '$current'"
echo $cmd
`$cmd`
echo `defaults read com.Growl.GrowlHelperApp LastUpdateCheck`

Answer 1

Don’t put the command in a variable, the quoting doesn’t work the way you think it does (see BashFAQ #050: I’m trying to put a command in a variable, but the complex cases always fail!). (And BTW the echo $cmd is not telling you what command will actually be executed). Just run the command directly.

Also, I presume you’re trying to run defaults write ..., not defaults read .... Finally, the echo and backquotes on the last line effectively cancel each other — just remove both. Here’s what I get:

#!/bin/sh
current=$(date +"%Y-%m-%d %l:%M:%S +0000")
defaults write com.Growl.GrowlHelperApp LastUpdateCheck -date "$current"
printf "New value of LastUpdateCheck: "
defaults read com.Growl.GrowlHelperApp LastUpdateCheck

If, for some reason, you actually do need to store the command in a variable before executing it, use an array. But note that this is a bash-only feature, so start the script with #!/bin/bash:

#!/bin/bash
current=$(date +"%Y-%m-%d %l:%M:%S +0000")
cmd=(defaults write com.Growl.GrowlHelperApp LastUpdateCheck -date "$current")
printf "About to execute:"
printf " %q" "${cmd[@]}"  # Need to use printf trickery to get appropriate quoting
printf "\n"
"${cmd[@]}"
printf "New value of LastUpdateCheck: "
defaults read com.Growl.GrowlHelperApp LastUpdateCheck