topic Re: cat /file to varaible in Operating System - HP-UX

cat /file to varaible

Piotr Kirklewski — Fri, 02 Apr 2010 05:04:54 GMT

Hi there I'm trying to crate a script which reads a log file content. Ho do I get an output of:

cat /somefile.log to a string in Unix shell ?

Regards
Peter

Re: cat /file to varaible

Matti_Kurkela — Fri, 02 Apr 2010 06:05:30 GMT

The output of any command (or a pipeline of commands) can be captured into a string by enclosing the command/pipeline with $( ).

For example, if you want to read the first line of a file to an environment variable, you might do something like this:

PIDVAR=$( head -1 /somewhere/file.pid )

However, if you simply want to read the entire contents of the file into a string, you can use $(< ). This is faster than using $(cat /somefile.log), as the shell does not have to fork a new "cat" process. If your script does something repeatedly in a tight loop, this might have a significant effect on performance.

Your example file could be read into a LOGVARIABLE by:

LOGVARIABLE=$(< /somefile.log )

MK

Re: cat /file to varaible

Laurent Menase — Fri, 02 Apr 2010 07:16:59 GMT

if you want to read it line by line you can also do

typeset -i b=0
while read a
do
b=b+1
echo line "$b:$a"
done

or
exec 3while read -u3 a
do
b=b+1
echo line "$b:$a"
done

Re: cat /file to variable

Dennis Handly — Sun, 21 Aug 2011 22:58:07 GMT

>Laurent: b=b+1

You'll need to use: (( b = b + 1 ))

Or: (( b += 1 ))

>exec 3< somefile.log

You should probably close it when you are done:
exec 3<&-

Re: cat /file to varaible

James R. Ferguson — Fri, 02 Apr 2010 09:55:14 GMT

Hi Peter:

You can also create/capture a shell 'here-document' into a string should the need arise:

LIST=$(
while read LINE
do
echo ${LINE}
done <<- EOF!
file1
file2
file3
EOF!
)
echo ${LIST}

Regards!

...JRF...

Re: cat /file to varaible

Suraj K Sankari — Fri, 02 Apr 2010 10:22:35 GMT

Hi,

>>Hi there I'm trying to crate a script which reads a log file content. Ho do I get an output of:

you can try to grep the strings which you are searching in log.
like if i need to search EMS strings in /var/adm/syslog/syslog.log then I will do

grep -i ems /var/adm/syslog/syslog.log

Suraj

Re: cat /file to varaible

Laurent Menase — Fri, 02 Apr 2010 10:53:35 GMT

>>Laurent: b=b+1
>You'll need to use: (( b = b + 1 ))
No in ksh or posix shell since I typed b with
typeset -i b=0, I don't need to use
(( ))

# typeset -i b=0
# b=b+1
# echo $b
1
# b=b+1
# echo $b
2

>>exec 3< somefile.log

>You should probably close it when you are >done:
>exec 3<&-
indeed it is cleaner to close it once the loop read all the file so at loop exit.

Re: cat /file to varaible

Piotr Kirklewski — Fri, 02 Apr 2010 21:06:34 GMT

Thanks for all the responses.
I got stock on the e-mail part. I was always using this:

echo "test" |mail -s "test" yyy@xxx.com

But this time I got the following error:
/usr/sbin/sendmail: Exec format error

If I try this:

cat /somefile.log << EOF | sendmail -t
to:xxx@yyy.com
from:xxx@yyy.com
subject:Testing 123
EOF

There is no error but I'm not getting the email either.

Please advice

Re: cat /file to varaible

Steven Schweda — Fri, 02 Apr 2010 22:50:06 GMT

> /usr/sbin/sendmail: Exec format error

uname -a
ls -l /usr/sbin/sendmail
file /usr/sbin/sendmail

Did "root" do something like
blah-blah-blah > /usr/sbin/sendmail
instead of:
blah-blah-blah | /usr/sbin/sendmail
?

Re: cat /file to varaible

Raj D. — Fri, 02 Apr 2010 22:54:02 GMT

Peter,

Instead of mail try mailx in hp-ux and it will work.

$ echo "test" |mailx -s "test-mail" yyy@xxx.com

More info :
http://docs.hp.com/en/5992-5835/ar01s04.html
( mailx example in : 2. b. )

Cheers,
Raj.

Re: cat /file to variable

Dennis Handly — Sun, 21 Aug 2011 22:59:01 GMT

>Laurent: No, in ksh or posix shell since I typed b with typeset -i b=0

Wow thanks! I tried it and it worked but it wasn't obvious where it was documented. I found it but it didn't have yellow highlighter on it. ;-)

Unfortunately you would have to use "" if you have spaces: b="b + 1"
So maybe using (( )) makes it more visually obvious.

>JRF: You can also create/capture a shell 'here-document' into a string should the need arise:

It might be cleaner to use an evil cat in this case. :-)
Unfortunately you can't use:
$(< <ccc
EOF
)
But you can replace that "<" by "cat".