Re: bash null conditional

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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?

Craig


I think it's simple:

The if sequence is only testing if the strings "grep A121 myfile.csv" or "grep A125 myfile.csv" have a non zero lentgh, and both strings have definitively non zero length. No grep cmd is executed.

If you want the grep commands to be executed and check the grep output, you must use $(grep ...) or `grep ...`.

--

Joachim Backes <joachim.backes@xxxxxxxxxxxxxx>

Attachment: smime.p7s
Description: S/MIME Cryptographic Signature

-- 
fedora-list mailing list
fedora-list@xxxxxxxxxx
To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
[Index of Archives]     [Older Fedora Users]     [Fedora Announce]     [Fedora Package Announce]     [EPEL Announce]     [Fedora Magazine]     [Fedora News]     [Fedora Summer Coding]     [Fedora Laptop]     [Fedora Cloud]     [Fedora Advisory Board]     [Fedora Education]     [Fedora Security]     [Fedora Scitech]     [Fedora Robotics]     [Fedora Maintainers]     [Fedora Infrastructure]     [Fedora Websites]     [Anaconda Devel]     [Fedora Devel Java]     [Fedora Legacy]     [Fedora Desktop]     [Fedora Fonts]     [ATA RAID]     [Fedora Marketing]     [Fedora Management Tools]     [Fedora Mentors]     [SSH]     [Fedora Package Review]     [Fedora R Devel]     [Fedora PHP Devel]     [Kickstart]     [Fedora Music]     [Fedora Packaging]     [Centos]     [Fedora SELinux]     [Fedora Legal]     [Fedora Kernel]     [Fedora OCaml]     [Coolkey]     [Virtualization Tools]     [ET Management Tools]     [Yum Users]     [Tux]     [Yosemite News]     [Gnome Users]     [KDE Users]     [Fedora Art]     [Fedora Docs]     [Asterisk PBX]     [Fedora Sparc]     [Fedora Universal Network Connector]     [Libvirt Users]     [Fedora ARM]

  Powered by Linux