On Mon, 2009-03-30 at 13:42 -0500, Robert Nichols wrote: > Craig White wrote: > > I'm in my bash book and looking on web but can't seem to resolve this > > simple problem. > > > > $ if [ -n "grep A121 myfile.csv" ]; then echo "null"; fi > > null > > > > $ if [ -n "grep A125 myfile.csv" ]; then echo "null"; fi > > null > > > > A125 definitely is null when I just run the grep command in the quotes > > but A121 definitely is not null. > > > > What am I missing on the if/null operator here? > > As written, you are asking if the literal string "grep A121 myfile.csv" > is non-null, which obviously is true and has nothing whatsoever to do > with the 'grep' command, which is never invoked. > > $ if [ -n "`grep A121 myfile.csv`" ]; then echo "null"; fi > > This will actually invoke 'grep' and insert its output into the string > to be tested. ---- yeah...I actually started with backticks and was trying various things. This seems to work... $ if [ `grep -c A121 myfile.csv` -eq 0 ]; then echo "null"; fi $ if [ `grep -c A125 myfile.csv` -eq 0 ]; then echo "null"; fi null $ but if someone clarifies the -n (null) result, I would be grateful. Thanks Craig -- fedora-list mailing list fedora-list@xxxxxxxxxx To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
