Piping is for plumbers and cake decoration. Try and avoid it as it will reduce the efficiency. In fact I've only just linked to an example of what @mm2270 was alluding to, regarding overhead on scripts.
Recon -realname syntax issue (bash)
Collecting Email Address via AD
If you take the basics of these examples (as shown below) you can see that there is a distinct difference it timing between the initial posted script and the supplied alternative. In fact the original script is only 7 lines of code, whilst the faster is 11. So the script is over 50% larger and yet ran in 2/3 the time.
Two main reasons:
- dscl was run only once and is calling the local files which has the same data
- there is no piping to awk
Yes the real time is a fraction of a second, but this example is tiny and as mentioned all this will add up (and remember, not only will it increase the time taken to recon, but someone is probably trying to use the machine at the same time, so think about what you are scripting).
#!/bin/bash
# Script name getADPipes.sh
CurrentUserName=$(whoami)
ADUserHomeCity=$(dscl /Active Directory/DOMAIN -read /Users/$CurrentUserName | awk '$1 == "City:" { print $2}')
ADUserFirstName=$(dscl /Active Directory/DOMAIN -read /Users/$CurrentUserName | awk '$1 == "FirstName:" { print $2}')
ADUserLastName=$(dscl /Active Directory/DOMAIN -read /Users/$CurrentUserName | awk '$1 == "LastName:" { print $2}')
ADUserEMailAddress=$(dscl /Active Directory/DOMAIN -read /Users/$CurrentUserName | awk '$1 == "EMailAddress:" { print $2}')
exit 0
$ time ./getADPipes.sh
real 0m0.056s
user 0m0.028s
sys 0m0.026s
#!/bin/bash
# Script name getAD.sh
loggedInUser=`stat -f%Su /dev/console`
plistbuddy="/usr/libexec/PlistBuddy"
tempFile="/tmp/dscl.plist"
dscl -plist . read /Users/$loggedInUser EMailAddress City RealName LastName FirstName > $tempFile
userEmail=`$plistbuddy -c "Print dsAttrTypeStandard:EMailAddress:0" $tempFile`
userCity=`$plistbuddy -c "Print dsAttrTypeStandard:City:0" $tempFile`
userLastName=`$plistbuddy -c "Print dsAttrTypeStandard:LastName:0" $tempFile`
userFirstName=`$plistbuddy -c "Print dsAttrTypeStandard:FirstName:0" $tempFile`
exit 0
$ time ./getAD.sh
real 0m0.038s
user 0m0.025s
sys 0m0.017s
It may also be worth considering how often the information you require is changing.
Examples:
- If it only changes once per login, perhaps the script could be a login script that writes to a plist and the EA reads the plist instead of trying to run the whole script.
- Perhaps a launch agent may be better placed to run the script as perhaps a watch folder and again you could write the data to a plist to read as an EA.
The more efficient they are, the more you can get away with.
