it may come from
find . . . | grep <some file name>
which is easier to remember than the method for incorporating the grep
verb in a find command.
On 08/25/2014 07:51 PM, Michael Havens wrote:
I get it!
cat x | grep y
is redundant. did I learn that when it wasn't redundant? if it never has
been redundant I wonder why I thought the pipe was needed?
:-)~MIKE~(-:
On Mon, Aug 25, 2014 at 4:25 PM, Brian Cluff <[email protected]
<mailto:[email protected]>> wrote:
You'll need to add some single quotes to keep the shell from
interpreting your regex as shell code like this:
grep -E 'error|fail' {make,install,check}.fail
Without the single quotes you are telling the system to cat from
your set of files and look for lines with the word error and pipe
that to a program called fail.
I found that I did have to add the -E even thought the man page says
that in the GNU version of grep the basic and extended regular
expressions are the same... it appears that is not the case in practice.
Brian Cluff
On 08/25/2014 12:56 PM, Michael Havens wrote:
I have 3 files, make.fail, install.fail, and check.fail. I want
to check
for two words in those files: error and fail.
would this work?
cat {make,install,check}.fail | grep -i error|fail
I was told to put the 'E' option in to grep. Looking at the man
page it
seems that the E option is only useful if I were greping for
something
that begins with a '{'. AM I misreading the man page?
man quote:
GNU grep -E attempts to support traditional usage by
assuming
that { is
not special if it would be the start of an
invalid
interval
specification. For example, the command grep -E '{1'
searches
for the
two-character string {1 instead of reporting a
syntax error
in the
regular expression. POSIX allows this behavior as an
extension, but
portable scripts should avoid it.
:-)~MIKE~(-:
On Mon, Aug 25, 2014 at 12:24 PM, Michael Havens
<[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>> wrote:
you guys are so helpful! Thanks.
:-)~MIKE~(-:
On Sun, Aug 24, 2014 at 7:40 PM, Jon Kettenhofen
<[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>> wrote:
I like visible proofs, so here's a test I ran:
(terminal output was as is shown)
[jon@localhost ~]$ rm temp
[jon@localhost ~]$ echo >>temp
[jon@localhost ~]$ echo $?
0
[jon@localhost ~]$ cat temp
[jon@localhost ~]$ echo >>temp 2>&1
[jon@localhost ~]$ echo $?
0
[jon@localhost ~]$ cat temp
[jon@localhost ~]$
as you can see, no errors and the single ">" did not
erase the
file when used in this manner. So Mike's script should
work as
intended
at least if there is no stderr output.
but suppose there was an error? (apologizing for the
length of ...)
[jon@localhost ~]$ echo "echo" >test
[jon@localhost ~]$ echo "ls temp2" >>test
[jon@localhost ~]$ # test ls of non-existent file
[jon@localhost ~]$ ls temp2
ls: cannot access temp2: No such file or directory
[jon@localhost ~]$ echo $?
2
[jon@localhost ~]$ # see, we get both an error and
stderr message
[jon@localhost ~]$ # so
[jon@localhost ~]$ mv test test.sh
[jon@localhost ~]$ chgmod +x test.sh
bash: chgmod: command not found...
[jon@localhost ~]$ chmod +x test.sh
[jon@localhost ~]$ # i'm not perfect!
[jon@localhost ~]$ rm temp
[jon@localhost ~]$ ./test.sh >>temp
ls: cannot access temp2: No such file or directory
[jon@localhost ~]$ echo $?
2
[jon@localhost ~]$ cat temp
[jon@localhost ~]$ ./test.sh >>temp 2>&1
[jon@localhost ~]$ echo $?
2
[jon@localhost ~]$ cat temp
ls: cannot access temp2: No such file or directory
[jon@localhost ~]$
as you can see, Mike's script will work as he
apparently intended,
providing he's using a modern version of bash.
On 08/24/2014 09:56 PM, James Mcphee wrote:
you've said make, append stdout (default file
descriptor 1)
to file
make.fail, assign stderr (default filedescriptor 2)
the same
filedescriptor as stdout. So... If the intent was
to have
both stderr
and stdout append make.fail, then it is correct.
On Sun, Aug 24, 2014 at 6:06 PM, Michael Havens
<[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>
<mailto:[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>>> wrote:
what I really need to know is will this:
make>>make.fail 2>&1
send stderr and stdout to the file 'make.fail'
or did I
write it
incorrectly?
:-)~MIKE~(-:
On Sun, Aug 24, 2014 at 2:56 PM, Brian Cluff
<[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>
<mailto:[email protected]
<mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>>>
wrote:
the > will delete any file that it points
at even
if the command
doesn't actually output anything. It will
even
delete the file
is the command doesn't exist like if you
type grep
as gerp
>file, file will still be
created/overwritten.
If you want to make sure that your command
doesn't
overwrite any
existing files you have to set the
noclobber option
like:
$ set -o noclobber
A good trick to know:
You can use the > to delete the contents
of a file
without
having to delete and recreate the file by
simply
doing this:
$ >yourfile
Brian Cluff
On 08/24/2014 02:36 PM, Michael Havens wrote:
I have a question about redirections:
make>>make.fail 2>&1
tells it make and then to send (>)
stderr (2)
to stdout (1)
and also to
send stdout that way also (&1).
finally all of
that gets
sent to a file
named make.fail (>>). Isn't '>>' actually
'append' whereas
'>' would
work just as well so long as the file
didn't
already exist?
If the file
did exist would I get an error or
would the
file be overwritten?
:-)~MIKE~(-:
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