linuxcommand-discuss

[Linuxcommand-discuss] question about redirection

[Bram M. <bra...@li...>]

Hi

I would like to use the following script to start evolution from now on
so the output would be logged.

Can I replace the "/data/logs/evolution.log" with a variable?  Right now
it looks quite ugly and reusing the script for other apps would involve
too much typing/a high risk of typos/not enough laziness :)

--- script ---
#!/bin/bash

echo "" >> /data/logs/evolution.log
echo "--- $(date +"%R %A, %B %-d, %Y") ---" >> /data/logs/evolution.log
evolution >> /data/logs/evolution.log 2>&1
---  end   ---
Can I replace it with something like:
--- script ---
#!/bin/bash

logfile="/data/logs/evolution.log"

echo "" >> $logfile
echo "--- $(date +"%R %A, %B %-d, %Y") ---" >> $logfile
evolution >> $logfile 2>&1
---  end   ---

TIA
-- 
# Mertens Bram "M8ram"   <bra...@li...>     Linux User #249103 #
# SuSE 8.2 Pro     kernel 2.4.20-4GB      i686                128MB RAM #
#   3:30pm  up 19 days 19:08,  6 users,  load average: 0.37, 0.27, 0.12 #

Re: [Linuxcommand-discuss] question about redirection

[William S. <bs...@pa...>]

Yes, by all means you would want to use a variable instead.  It would make
your script easier to maintain.  I would suggest that in keeping with
convention, the name of the variable should have an uppercase name since
it you are treating the variable as a constant.


|||||  William Shotts, Jr. (bshotts AT panix DOT com)
|||||  Be a Linux Commander!  Follow me to http://linuxcommand.org

On Wed, 11 Feb 2004, Bram Mertens wrote:

> Hi
>
> I would like to use the following script to start evolution from now on
> so the output would be logged.
>
> Can I replace the "/data/logs/evolution.log" with a variable?  Right now
> it looks quite ugly and reusing the script for other apps would involve
> too much typing/a high risk of typos/not enough laziness :)
>
> --- script ---
> #!/bin/bash
>
> echo "" >> /data/logs/evolution.log
> echo "--- $(date +"%R %A, %B %-d, %Y") ---" >> /data/logs/evolution.log
> evolution >> /data/logs/evolution.log 2>&1
> ---  end   ---
> Can I replace it with something like:
> --- script ---
> #!/bin/bash
>
> logfile="/data/logs/evolution.log"
>
> echo "" >> $logfile
> echo "--- $(date +"%R %A, %B %-d, %Y") ---" >> $logfile
> evolution >> $logfile 2>&1
> ---  end   ---

Re: [Linuxcommand-discuss] question about redirection

[Bram M. <bra...@li...>]

On Wed, 2004-02-11 at 15:51, William Shotts wrote:
> Yes, by all means you would want to use a variable instead.  It would make
> your script easier to maintain.  I would suggest that in keeping with
> convention, the name of the variable should have an uppercase name since
> it you are treating the variable as a constant.

After editing the script I get the following errors:
m8ram@linux:~> bin/startevo
bin/startevo: line 3: =/data/logs/evolution.log: No such file or directory
bin/startevo: line 4: $LOGFILE: ambiguous redirect
bin/startevo: line 5: $LOGFILE: ambiguous redirect
bin/startevo: line 6: $LOGFILE: ambiguous redirect

This is what the script looks like now:
m8ram@linux:~> cat bin/startevo
#!/bin/bash

$LOGFILE="/data/logs/evolution.log"
echo "" >> $LOGFILE
echo "--- $(date +"%R %A, %B %-d, %Y") ---" >> $LOGFILE
evolution >> $LOGFILE 2>&1

The file does exist and is writable:
m8ram@linux:~> ls -lh /data/logs/evolution.log 
-rw-r--r--    1 m8ram    users         50K 2004-02-11 16:58 /data/logs/evolution.log

Why is bash looking for a file called '=/data/logs/evolution.log' ?  The
quotes are correct, aren't they?

TIA
-- 
# Mertens Bram "M8ram"   <bra...@li...>     Linux User #249103 #
# SuSE 8.2 Pro     kernel 2.4.20-4GB      i686                128MB RAM #
#   5:06pm  up 19 days 20:43,  5 users,  load average: 0.56, 0.20, 0.10 #

Re: [Linuxcommand-discuss] question about redirection

[William S. <bs...@pa...>]

I see your problem.  See my comment below...

|||||  William Shotts, Jr. (bshotts AT panix DOT com)
|||||  Be a Linux Commander!  Follow me to http://linuxcommand.org

On Wed, 11 Feb 2004, Bram Mertens wrote:

> On Wed, 2004-02-11 at 15:51, William Shotts wrote:
> > Yes, by all means you would want to use a variable instead.  It would make
> > your script easier to maintain.  I would suggest that in keeping with
> > convention, the name of the variable should have an uppercase name since
> > it you are treating the variable as a constant.
>
> After editing the script I get the following errors:
> m8ram@linux:~> bin/startevo
> bin/startevo: line 3: =/data/logs/evolution.log: No such file or directory
> bin/startevo: line 4: $LOGFILE: ambiguous redirect
> bin/startevo: line 5: $LOGFILE: ambiguous redirect
> bin/startevo: line 6: $LOGFILE: ambiguous redirect
>
> This is what the script looks like now:
> m8ram@linux:~> cat bin/startevo
> #!/bin/bash
>
> $LOGFILE="/data/logs/evolution.log"

This is wrong.
It should be:

LOGFILE="/data/logs/evolution.log"

No leading "$".  $ tells bash to perform a substition.  It does not
indicate a variable type as it would in say VisualBasic.

Also, I assume that /data/logs exists and you have permission to
read/write a file in that directory.

> echo "" >> $LOGFILE
> echo "--- $(date +"%R %A, %B %-d, %Y") ---" >> $LOGFILE
> evolution >> $LOGFILE 2>&1
>
> The file does exist and is writable:
> m8ram@linux:~> ls -lh /data/logs/evolution.log
> -rw-r--r--    1 m8ram    users         50K 2004-02-11 16:58 /data/logs/evolution.log
>
> Why is bash looking for a file called '=/data/logs/evolution.log' ?  The
> quotes are correct, aren't they?
>
> TIA
> --
> # Mertens Bram "M8ram"   <bra...@li...>     Linux User #249103 #
> # SuSE 8.2 Pro     kernel 2.4.20-4GB      i686                128MB RAM #
> #   5:06pm  up 19 days 20:43,  5 users,  load average: 0.56, 0.20, 0.10 #
>
>
>
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Re: [Linuxcommand-discuss] question about redirection

[Bram M. <bra...@li...>]

On Wed, 2004-02-11 at 18:56, William Shotts wrote:
> I see your problem.  See my comment below...
[...]
> > $LOGFILE="/data/logs/evolution.log"
> 
> This is wrong.
> It should be:
> 
> LOGFILE="/data/logs/evolution.log"
> 
> No leading "$".  $ tells bash to perform a substition.  It does not
> indicate a variable type as it would in say VisualBasic.

Thanks that did it indeed, I also changed:
echo "" >> $LOGFILE
echo "--- $(date +"%R %A, %B %-d, %Y") ---" >> $LOGFILE
to:
echo "\n--- $(date +"%R %A, %B %-d, %Y") ---" >> $LOGFILE

Just to clean things up.

Regards

Bram
-- 
# Mertens Bram "M8ram"   <bra...@li...>     Linux User #249103 #
# SuSE 8.2 Pro     kernel 2.4.20-4GB      i686                128MB RAM #
#  11:26pm  up 20 days  3:04,  5 users,  load average: 0.01, 0.05, 0.01 #

Re: [Linuxcommand-discuss] question about redirection

[Bram M. <bra...@li...>]

On Wed, 2004-02-11 at 23:26, Bram Mertens wrote:
[...]
> Thanks that did it indeed, I also changed:
> echo "" >> $LOGFILE
> echo "--- $(date +"%R %A, %B %-d, %Y") ---" >> $LOGFILE
> to:
> echo "\n--- $(date +"%R %A, %B %-d, %Y") ---" >> $LOGFILE

Hmm that didn't work as expected either, after looking at `info echo` I
realised it had to be:
echo -e "\n--- $(date +"%R %A, %B %-d, %Y") ---" >> $LOGFILE

Regards
-- 
# Mertens Bram "M8ram"   <bra...@li...>     Linux User #249103 #
# SuSE 8.2 Pro     kernel 2.4.20-4GB      i686                128MB RAM #
#  11:32pm  up 20 days  3:10,  5 users,  load average: 0.44, 0.19, 0.08 #

Re: [Linuxcommand-discuss] question about redirection

[William S. <bs...@pa...>]

You got it.

|||||  William Shotts, Jr. (bshotts AT panix DOT com)
|||||  Be a Linux Commander!  Follow me to http://linuxcommand.org