topic Re: Message redirection in Operating System - HP-UX

Message redirection

Chakravarthi — Wed, 20 Nov 2002 10:29:52 GMT

Hi all,

I'm running an application, it prints lot of printf statements on the terminal, i want to redirect all of the messages to a log file,

i tried doing this using "command > lofile 2>&1", this doesnt work, but the same command works for all unix commands. Is there any other way to capture the messages

regards
chakri

Re: Message redirection

Chris Wilshaw — Wed, 20 Nov 2002 10:37:11 GMT

You can do either

command | tee -a logfile

or

script logfile
command

The script option may be preferable, as this also captures any user keystrokes involved during the process.

Re: Message redirection

Chuck J — Wed, 20 Nov 2002 10:54:45 GMT

You can do:

# script

when you've finished you do a CTRL+D to end the log file. You can then cat, more, print or do whatever with the logfile.

Chuck J

Re: Message redirection

Chakravarthi — Wed, 20 Nov 2002 11:02:00 GMT

sorry tee is not working

Re: Message redirection

Chakravarthi — Wed, 20 Nov 2002 11:02:45 GMT

Hi,

tee is also working,, the program is a C program, with lot of printf statements, script works, but the problem with script is i can see the log only after closing the program,

Is there anyway i can get the log messages without closing the application

regards
chakri

Re: Message redirection

Chuck J — Wed, 20 Nov 2002 11:21:15 GMT

Open a 2nd window and do a tail -f on your log file:

# tail -f logfile

This will update whenever the logfile gets written to.

Don't forget to assign us points please :-)

Chuck J

Re: Message redirection

Chakravarthi — Wed, 20 Nov 2002 11:26:33 GMT

I'm trying this on linux machine, it is not saving the messages until i close the session,,,

Re: Message redirection

Darrell Allen — Wed, 20 Nov 2002 15:16:53 GMT

Hi,

Here's a guess as to why "this doesnt work, but the same command works for all unix commands".

The application has redirected stdout to the tty device, effectively over-riding what you are attempting with "command >lofile 2>&1".

Check with the application developer to see if that's the case.

Consider the following simple test...

# cat script
#!/usr/bin/sh
echo first message
TTY=$(tty)
echo second message >$TTY

# ./script
first message
second message

# ll
total 2
-rwx------ 1 root sys 57 Nov 20 10:07 script

# ./script >out
second message

# ll
total 4
-rw-r--r-- 1 root sys 14 Nov 20 10:07 out
-rwx------ 1 root sys 57 Nov 20 10:07 script

# cat out
first message

Darrell