[SOLVED] Print first "n" lines of all files within a directory

danielbmartin · 10-13-2014, 07:16 AM

Having identified a directory, it is desired to print the first 4 lines of every file within that directory.
The chosen directory contains many files and a few sub-directories.
find works recursively, and that's desirable.

This code ...

Code:

DoI='/home/daniel/Desktop/LQfiles'  # DoI=Directory of Interest
find $DoI        \
|xargs  head -4  \
>$Work2

... produces the desired result but also flashes error messages to the screen, such as ...

Code:

head: error reading `/home/daniel/Desktop/LQfiles': Is a directory
head: error reading `/home/daniel/Desktop/LQfiles/LQ8': Is a directory
head: error reading `/home/daniel/Desktop/LQfiles/LQ6': Is a directory
head: error reading `/home/daniel/Desktop/LQfiles/LQ7': Is a directory

How may these undesirable messages be eliminated?

Is there an option for find which should be used?
(I looked but did not find one.)
Is there a way to redirect the error messages to a different file?
(I tried to do that but botched it.)

Please advise.

Daniel B. Martin

schneidz · 10-13-2014, 07:59 AM

i think you can append

Code:

2 > /dev/null

to the command to mask the problem.

maybe try exec within find:

Code:

find $DoI -type f -exec head -n 4 '{}' \;

danielbmartin · 10-13-2014, 09:02 AM

Thank you, schneidz, for the suggestions.

This code ...

Code:

find $DoI |xargs head -4 >$Work2 2 > /dev/null

... produced the same on-screen error messages.

This code ...

Code:

find $DoI -type f -exec head -n 4 '{}' >$Work3

... produced this error message ...

Code:

find: missing argument to `-exec'

I'm running Ubuntu 10.04, a back level. Could this be a problem?

Daniel B. Martin

schneidz · 10-13-2014, 09:05 AM

i doubt version would be a problem.

sorry, there should be no space between 2 and >:

Code:

2> /dev/null

for the find command you copy-pastad wrong:

Code:

find $DoI -type f -exec head -n 4 '{}' \;

danielbmartin · 10-13-2014, 09:11 AM

Success! Thank you, schneidz, for the guidance.

This code ...

Code:

find $DoI |xargs head -4 >$Work2 2> /dev/null

... runs cleanly.

This code ...

Code:

find $DoI |xargs head -4 >$Work2 2> $Errors

... also runs cleanly and preserves the error messages for reference.

SOLVED!

Daniel B. Martin

schneidz · 10-13-2014, 09:14 AM

this is ideal since it explicitly tells find to limit its searching to type files (and ignore directories so that head doesnt try to print them (which doesnt make much sense anyways)):

Code:

find $DoI -type f -exec head -n 4 '{}' \;

the previous code will mask any problems making debugging difficult