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shellsolaris-10

how to match /data1 as word with the help of grep

I am using Solaris 5.10 and working on Bash Shell. I have a shell script in which the following statement not working

ssh 172.18.16.55 "df -h" |grep -w /data1

When I replace /data1 with data1 (i.e removed "/"), it is working correctly.

I have another statement like below which is working fine.

ssh 172.18.16.55 "df -h" |grep -w /dev/dsk/c1t0d0s0

According to my understanding, first occurrence of "/" (forward slash) is not getting recognized by the shell script. I want to know what is the significance of "/" in shell script? below are my outputs.

root@P020XIDCNF # ssh 172.18.16.55 "df -h" |grep '/data1\>'
/dev/md/dsk/d50         84G    59G    24G    71%    /data1

root@P020XIDCNF # ssh 172.18.16.55 "df -h" |grep -w /data1

does not print anything.

root@P020XIDCNF # ssh 172.18.16.55 "df -h" |grep /data1
/dev/md/dsk/d50         84G    59G    24G    71%    /data1
Solution

  • grep's -w option tells to match the pattern as a "word", i.e., with a "word boundary" before and after it. I think what's happening is that grep's idea of a word boundary doesn't match what you're expecting.

    You can use \< and \> to match word boundaries explicitly.

    Here are some examples run on a Solaris 9 system:

    % echo /dev/md/dsk/d50 84G 59G 25G 71% /data1 | grep -w /data1
% echo /dev/md/dsk/d50 84G 59G 25G 71% /data1 | grep '\</data1\>'
% echo /dev/md/dsk/d50 84G 59G 25G 71% /data1 | grep '/data1\>'  
/dev/md/dsk/d50 84G 59G 25G 71% /data1
%

    Apparently Solaris grep doesn't consider the the boundary between a space and a / character to be a word boundary.

    I suggest running man grep, and probably following some of the "See also" references, to see just how this is documented. (I tried to do that myself, but the Solaris system I have access to is having problems at the moment.)

    If you want to use this command as part of a reasonably portable script, you need to be aware that this is an area where GNU grep behaves differently. I get the following on my Linux system with GNU grep:

    % echo /dev/md/dsk/d50 84G 59G 25G 71% /data1 | grep -w /data1
/dev/md/dsk/d50 84G 59G 25G 71% /data1
% echo /dev/md/dsk/d50 84G 59G 25G 71% /data1 | grep '\</data1\>'
% echo /dev/md/dsk/d50 84G 59G 25G 71% /data1 | grep '/data1\>'  
/dev/md/dsk/d50 84G 59G 25G 71% /data1
%

    Note that your question would have been easier to answer if you had shown us the exact line that you expected to be matched.