How to list the first 10 lines error from executing command

[Barry Margolin]

In article <1673c1fd.0307291148.7fd25c2e@posting.google.com >,
John <johnwu@yorku.ca> wrote:

>Hello All
>
>I know this is a common question, but I didn't know how to search and
>get its answer, say if the following command end up with lots lines of
>error,
>
>javac file.java
>javac find error:file.java error 1111
>file.java:error 22222...
>....
>
>how to let it just displaying the first 10 lines of error, something
>like
>
>more a_file | head -10 #or
>cat a_file | grep "myError"

javac file.java 2>&1 | head -10

2>&1 means to redirect stderr to where stdout goes, and then you can use
the familiar piping of stdout to post-process that.

--
Barry Margolin, [email]barry.margolin@level3.com[/email]
Level(3), Woburn, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.

[Joe Halpin]

[email]johnwu@yorku.ca[/email] (John) writes:

> Hello All
>
> I know this is a common question, but I didn't know how to search
> and get its answer, say if the following command end up with lots
> lines of error,
>
> javac file.java
> javac find error:file.java error 1111
> file.java:error 22222...
> ....
>
> how to let it just displaying the first 10 lines of error, something
> like
>
> more a_file | head -10 #or
> cat a_file | grep "myError"

Try

javac file.java 2>&1 >/dev/null | head -10

Joe

[JohnWu]

"Joe Halpin" <jhalpin@nortelnetworks.com_.nospam> wrote in message
news:yxs7n0exm6zv.fsf@nortelnetworks.com_.nospam.. .

> Try
>
> javac file.java 2>&1 >/dev/null | head -10
>
> Joe

Thanks, Joe

In sh, it works, but I'm using tcsh and csh, it said that it was ambiguous
redirect output, do you mind telling me again how to do it for tcsh, or csh?

--
Best Regards
John

[Chris F.A. Johnson]

On Wed, 30 Jul 2003 at 01:34 GMT, JohnWu wrote:

>
> "Joe Halpin" <jhalpin@nortelnetworks.com_.nospam> wrote in message
> news:yxs7n0exm6zv.fsf@nortelnetworks.com_.nospam.. .

>> Try
>>
>> javac file.java 2>&1 >/dev/null | head -10

>
> In sh, it works, but I'm using tcsh and csh, it said that it was ambiguous
> redirect output, do you mind telling me again how to do it for tcsh, or csh?

Redirection is one of the things that [t]csh doesn't handle well.

Why don't you use a Bourne-type shell? [T]csh is not recommended
for scripting.

--
Chris F.A. Johnson [url]http://cfaj.freeshell.org[/url]
================================================== =================
My code (if any) in this post is copyright 2003, Chris F.A. Johnson
and may be copied under the terms of the GNU General Public License

[JohnWu]

"Chris F.A. Johnson" <c.f.a.johnson@rogers.com> wrote in message
news:bg7ciq$lhnck$1@ID-136730.news.uni-berlin.de...

> Redirection is one of the things that [t]csh doesn't handle well.
>
> Why don't you use a Bourne-type shell? [T]csh is not recommended
> for scripting.
>

Bourne Shell is better, I agree. The things to me are, my account's default
shell is set to tcsh, and some of the commands linked to DB2 and other
softwares only work in tcsh (guess this can be fixed).

Anyway, the inconvenience for me to use Bourne Shell is that, I don't know
how to set up or configure the environment, so that whenever login to my
account in Solaris 5.8, the (Left and Right) arrows keys can display the
command histroy,so that long command line can be issued by a Arrow key
javac -classpath ..... file.java .....

--
Thanks
John

[JohnWu]

> You can't redirect stderr separate from stdout in csh, only both, like

> this:
>
> javac file.java |& head -10
> javac file.java |& more
>
> (man csh:
> A simple command, or a set of simple commands separated by |
> or |& characters, forms a pipeline. With |, the standard output
> of the preceding command is redirected to the standard input of
> the command that follows. With |&, both the standard error and
> the standard output are redirected through the pipeline.
> )
>

Thanks lots, that's what I wanted.
One more thing regarding Bourne-sh, as asked in previous thread, in sh, how
to set Arrow key to display history command, as in csh?
--
John
Toronto

[Joe Halpin]

"JohnWu" <johnwu@yorku.ca> writes:

> "Chris F.A. Johnson" <c.f.a.johnson@rogers.com> wrote in message
> news:bg7ciq$lhnck$1@ID-136730.news.uni-berlin.de...

> > Redirection is one of the things that [t]csh doesn't handle well.
> >
> > Why don't you use a Bourne-type shell? [T]csh is not recommended
> > for scripting.
> >

> Bourne Shell is better, I agree. The things to me are, my account's
> default shell is set to tcsh, and some of the commands linked to DB2
> and other softwares only work in tcsh (guess this can be fixed).
>
> Anyway, the inconvenience for me to use Bourne Shell is that, I
> don't know how to set up or configure the environment, so that
> whenever login to my account in Solaris 5.8, the (Left and Right)
> arrows keys can display the command histroy,so that long command
> line can be issued by a Arrow key javac -classpath ..... file.java

If you use korn shell or bash you get (IMO) better command line recall
and editing than with csh, and you can choose between vi and emacs
editing modes.

Take a look at

[url]http://www.faqs.org/faqs/unix-faq/shell/shell-differences/[/url]

Joe

[Ralf Fassel]

* "JohnWu" <johnwu@yorku.ca>
| One more thing regarding Bourne-sh, as asked in previous thread, in
| sh, how to set Arrow key to display history command, as in csh?

You can't do this neither in plain sh, nor in regular csh. You can do
this in tcsh (enhanced version of csh) and in bash (enhanced GNU
version of sh). Other shells may have other editing features (such as
ksh's vi mode).

R'

[joe@invalid.address]

Ralf Fassel <ralfixx@gmx.de> writes:

> * "JohnWu" <johnwu@yorku.ca>
> | One more thing regarding Bourne-sh, as asked in previous thread, in
> | sh, how to set Arrow key to display history command, as in csh?
>
> You can't do this neither in plain sh, nor in regular csh. You can do
> this in tcsh (enhanced version of csh) and in bash (enhanced GNU
> version of sh). Other shells may have other editing features (such as
> ksh's vi mode).

In emacs mode (at least - I don't use vi mode) ksh and bash can both
use the arrow keys for command line recall. ksh needs some aliases
setup, but bash seems to do it builtin.

Joe