Shell Programming and Scripting

@agama

I have used this code :

Code:

find . -type f  ! -name test.txt |  xargs grep "491629461544"  >test.txt

It displays the Output with file name.

How to display the output without file name using the above command.

Regards,
Nanthagopal

The grep utility always includes the filename when more than one file is given on the command line so you determine where the matched line came from. Using xargs the way you are here will usually invoke grep with several file operands, but may invoke grep with only one file operand if find only finds one file to process or the xargs ends up with a single file arg on the last invocation of grep. If you want to be sure that grep is only called with one file operand, skip the xargs element of your pipeline and just use a -exec primary in the find command:

Code:

find . -type f  ! -name test.txt -exec grep "491629461544" {} \; > test.txt

---------- Post updated at 06:40 AM ---------- Previous update was at 03:15 AM ----------

The original command posted by nanthagopal was:

Code:

find . -type f -exec grep "491629461544"  {} \; > test.txt

The > test.txt creates text.txt as a regular file in the current directory. With "." being the root of the file hierarchy being searched by find, it will eventually reach a point where find invokes the command:

Code:

grep "491629461544" test.txt

with the output being appended to test.txt while it is being read. If the amount of text in the file when grep gets to it is small enough, it may hit end-of-file before it gets stuck in a loop copying previously matched lines to the end of the test.txt recursively until the disk fills up or the maximum file size limit is reached.

Later suggestions in this thread avoid the problem by excluding test.txt from the list of files to be processed by grep:

Code:

find . -type f  ! -name test.txt  ... > test.txt

Another way to avoid the problem is to direct the output to a file outside of the file hierarchy being search by the find, such as:

Code:

find . -type f ... > ../test.txt

It is true that some versions of the grep utility will refuse to process a file operand if it names the output file, but that is not required by the standards, and can't be relied upon in a portable script.

Adding -h to the grep command will eliminate the filename:

Code:

find . -type f  ! -name test.txt |  xargs grep -h "491629461544"  >test.txt

The grep -h option isn't in the standards, but it is present in all of the man page sets available in the Man Pages tab on this site. Thanks to agama for pointing out this option.