Want to search every file, in some directory and all its subdirectories, to find the file that has a particular word or string in it? That's a job for find and one of the grep ( 27.1 ) commands.
For example, to search all the files for lines starting with a number and containing the words "SALE PRICE," you could use:
%egrep '^[0-9].*SALE PRICE' `find . -type f -print`
./archive/ad.1290: 1.99 a special SALE PRICE ./archive/ad.0191: 2.49 a special SALE PRICE
Using the
backquotes (
9.16
)
(
``
) might not work. If
find
finds too many files,
egrep
's command-line arguments can
get too long (
9.20
)
. Using
xargs
(
9.21
)
can solve that; it splits long sets of arguments into smaller chunks. There's a problem with that: if the last "chunk" has just one filename and the
grep
command finds a match there,
grep
won't print the filename:
fgrep |
%
|
---|
The answer is to add the UNIX "empty file," /dev/null ( 13.14 ) . It's a filename that's guaranteed never to match but always to leave fgrep with at least two filenames:
%find . -type f -print | xargs fgrep '$12.99' /dev/null
Then xargs will run commands like:
fgrep '$12.99' /dev/null ./afile ./bfile ... fgrep '$12.99' /dev/null ./archives/ad.0190 ./archives/ad.0290 ... fgrep '$12.99' /dev/null ./old_sales/ad.1289
That trick is also good when you use a wildcard and only one file might match it. grep won't always print the file's name unless you add /dev/null :
%grep "
whatever
" /dev/null /x/y/z/a*
-