What does gdate mean in this shell script?

Question

I need to maintain this shell script:

export DAYDAY=`gdate --date "30 days ago" +"%Y%m%d"` 
if [ -d $TMP/AA/$DAYDAY]; then
    rm -r $TMP/AA/$DAYDAY  
fi

But I can't run it because it can't find gdate ; this code is to clear the log directory that is exactly 30 days old.

Answer 1

On *nix systems other than Linux it's fairly common for the GNU flavor of utilities to be installed prefixed with a g (eg gmake , gtar , etc). In this case, it's likely this refers to the GNU flavor of the date command. So, since you are on Linux, just change it to date :

export DAYDAY=`date --date "30 days ago" +"%Y%m%d"` 
if [ -d $TMP/AA/$DAYDAY]; then
    rm -r $TMP/AA/$DAYDAY  
fi

Answer 2

It's G NU's date ; called gdate on BSD-related systems to differentiate it from their own date .

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I work on Linux in a 90% Mac office and quite a few of my colleagues' scripts reference things like gsed and gdate . Where I couldn't fix this properly with a switch on $OSTYPE I eventually capitulated and did this:

sudo ln -s $(which date) /bin/gdate

This symlinks gdate to date .

This is quite safe because there should never be a gdate (or a gsed , gtar or gmake ), for the version installed on GNU/Linux is the GNU version, obviously.

You could also alias the command of course, but this carries over users and shells. It is in effect aliasing the whole program.