Re: bash question.
Hi John, On Thu, Apr 12, 2012 at 10:42:33PM -0500, John McKown wrote: bash has variables, such as $PATH and $HOME and maybe even $i. If a variable has been the subject of an export command, you find all of them which are export'd using the printenv command. But is there some way to find the ones which exist, but have not been export'd? No, I guess I don't have a real need for this. But I'm curious. You can use declare -p. Exported variables are displyed with -x, for example: declare -x EDITOR=vim Take a look at help declare for other options like if a variable is an array... -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: bash question.
I must learn how to read the manuals. Yes, I did do an info bash. It's nice and easy to use to find what a command does, if you know the command. But it is difficult, at least for me, to find a command based on what it does. -- John McKown Systems Engineer IV IT Administrative Services Group HealthMarkets(r) 9151 Boulevard 26 * N. Richland Hills * TX 76010 (817) 255-3225 phone * john.mck...@healthmarkets.com * www.HealthMarkets.com Confidentiality Notice: This e-mail message may contain confidential or proprietary information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. HealthMarkets(r) is the brand name for products underwritten and issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake Life Insurance Company(r), Mid-West National Life Insurance Company of TennesseeSM and The MEGA Life and Health Insurance Company.SM -Original Message- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Mark Post Sent: Thursday, April 12, 2012 10:48 PM To: LINUX-390@VM.MARIST.EDU Subject: Re: bash question. On 4/12/2012 at 11:42 PM, John McKown joa...@swbell.net wrote: bash has variables, such as $PATH and $HOME and maybe even $i. If a variable has been the subject of an export command, you find all of them which are export'd using the printenv command. But is there some way to find the ones which exist, but have not been export'd? I use env or set. Mark Post -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/ -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: bash question.
Very nice! Thanks. I guess that I'm going to end up dedicating a weekend day to just read the entire output from info bash. Luckily, I can create a text file from it, convert it to PDF format, then read the PDF directly on my Kindle DX or Android tablet. I really don't like reading manuals on my PC screen because it is landscape instead of portrait. -- John McKown Systems Engineer IV IT Administrative Services Group HealthMarkets(r) 9151 Boulevard 26 * N. Richland Hills * TX 76010 (817) 255-3225 phone * john.mck...@healthmarkets.com * www.HealthMarkets.com Confidentiality Notice: This e-mail message may contain confidential or proprietary information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. HealthMarkets(r) is the brand name for products underwritten and issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake Life Insurance Company(r), Mid-West National Life Insurance Company of TennesseeSM and The MEGA Life and Health Insurance Company.SM -Original Message- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Hendrik Brueckner Sent: Friday, April 13, 2012 3:47 AM To: LINUX-390@VM.MARIST.EDU Subject: Re: bash question. Hi John, On Thu, Apr 12, 2012 at 10:42:33PM -0500, John McKown wrote: bash has variables, such as $PATH and $HOME and maybe even $i. If a variable has been the subject of an export command, you find all of them which are export'd using the printenv command. But is there some way to find the ones which exist, but have not been export'd? No, I guess I don't have a real need for this. But I'm curious. You can use declare -p. Exported variables are displyed with -x, for example: declare -x EDITOR=vim Take a look at help declare for other options like if a variable is an array... -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/ -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: bash question.
McKown, John writes: Very nice! Thanks. I guess that I'm going to end up dedicating a weekend day to just read the entire output from info bash. Luckily, I can create a text file from it, convert it to PDF format, then read the PDF directly on my Kindle DX or Android tablet. In case you weren't aware of it already, the utilities used to process the *roff macros used in man pages support typesetting to PostScript as well as generating simple text output. So typing man -t bash bash-man.ps will generate you a nicely formatted PostScript version of the man page in bash-man.ps, fancy fonts and all, instead of what you'd get from just taking the text version. That's suitable for direct pringting but you can instead just ps2pdf bash-man.ps to produce your bash-man.pdf PDF version. Using info bash instead of man bash uses a slightly different source of documentation (the FSF document their own programs in their own GNU info format instead of man pages) but you'll nearly always find that some nice people have already ensured that your distro has man pages for the programs as well and that they have either exactly the same content or are close enough for most purposes. There are ways of generating various typeset-like formats from info format too but I forget what they are and I don't think they are as simple as just adding -t to your man command invocation. --Malcolm -- Malcolm Beattie Mainframe Systems and Software Business, Europe IBM UK -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: bash question.
Oh, that is beautiful! Thank you very much. -- John McKown Systems Engineer IV IT Administrative Services Group HealthMarkets(r) 9151 Boulevard 26 * N. Richland Hills * TX 76010 (817) 255-3225 phone * john.mck...@healthmarkets.com * www.HealthMarkets.com Confidentiality Notice: This e-mail message may contain confidential or proprietary information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. HealthMarkets(r) is the brand name for products underwritten and issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake Life Insurance Company(r), Mid-West National Life Insurance Company of TennesseeSM and The MEGA Life and Health Insurance Company.SM -Original Message- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Malcolm Beattie Sent: Friday, April 13, 2012 11:01 AM To: LINUX-390@VM.MARIST.EDU Subject: Re: bash question. snip In case you weren't aware of it already, the utilities used to process the *roff macros used in man pages support typesetting to PostScript as well as generating simple text output. So typing man -t bash bash-man.ps will generate you a nicely formatted PostScript version of the man page in bash-man.ps, fancy fonts and all, instead of what you'd get from just taking the text version. That's suitable for direct pringting but you can instead just ps2pdf bash-man.ps to produce your bash-man.pdf PDF version. Using info bash instead of man bash uses a slightly different source of documentation (the FSF document their own programs in their own GNU info format instead of man pages) but you'll nearly always find that some nice people have already ensured that your distro has man pages for the programs as well and that they have either exactly the same content or are close enough for most purposes. There are ways of generating various typeset-like formats from info format too but I forget what they are and I don't think they are as simple as just adding -t to your man command invocation. --Malcolm -- Malcolm Beattie -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
bash question.
bash has variables, such as $PATH and $HOME and maybe even $i. If a variable has been the subject of an export command, you find all of them which are export'd using the printenv command. But is there some way to find the ones which exist, but have not been export'd? No, I guess I don't have a real need for this. But I'm curious. -- John McKown Maranatha! -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: bash question.
On 4/12/2012 at 11:42 PM, John McKown joa...@swbell.net wrote: bash has variables, such as $PATH and $HOME and maybe even $i. If a variable has been the subject of an export command, you find all of them which are export'd using the printenv command. But is there some way to find the ones which exist, but have not been export'd? I use env or set. Mark Post -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
BASH question - may even be advanced - pipe stdout to 2 or more processes.
Yeah, it sound weird. What I have is 72 files containing a lot of secuity data from our z/OS RACF system. To save space, all these files are bzip2'ed - each individually. I am writing some Perl scripts to process this data. The Perl script basically reformats the data in such a way that I can put it easily into a PostgreSQL database. If I want to run each Perl script individually, it is simple: bzcat data*bz2 | perl script1.pl | psql database bzcat data*bz2 | perl script2.pl | psql database and so on. I don't want to try to merge the scripts together into a single, complicated, script. I like what I have in that regard. But I don't like running the bzcat twice to feed into each Pel script. Is something like the following possible? mkfifo script1.fifo mkfifo script2.fifo bzcat data*bz2 | tee script1.fifo script2.fifo perl script1.pl script1.fifo perl script2.pl script2.fifo ??? What about more than two scripts concurrently? What about n scripts? John McKown Systems Engineer IV IT Administrative Services Group HealthMarkets(r) 9151 Boulevard 26 * N. Richland Hills * TX 76010 (817) 255-3225 phone * john.mck...@healthmarkets.com * www.HealthMarkets.com Confidentiality Notice: This e-mail message may contain confidential or proprietary information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. HealthMarkets(r) is the brand name for products underwritten and issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake Life Insurance Company(r), Mid-West National Life Insurance Company of TennesseeSM and The MEGA Life and Health Insurance Company.SM -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: BASH question - may even be advanced - pipe stdout to 2 or more processes.
If you have a new enough bash, you can: bzcat data*bz2 | tee (process1) (process2) (process3) ... | processn but the stdout from process1..n get intermixed unless redirected to files. (Tom Meyer taught me that!) - Larry On 2/9/11 12:19 PM, McKown, John wrote: Yeah, it sound weird. What I have is 72 files containing a lot of secuity data from our z/OS RACF system. To save space, all these files are bzip2'ed - each individually. I am writing some Perl scripts to process this data. The Perl script basically reformats the data in such a way that I can put it easily into a PostgreSQL database. If I want to run each Perl script individually, it is simple: bzcat data*bz2 | perl script1.pl | psql database bzcat data*bz2 | perl script2.pl | psql database and so on. I don't want to try to merge the scripts together into a single, complicated, script. I like what I have in that regard. But I don't like running the bzcat twice to feed into each Pel script. Is something like the following possible? mkfifo script1.fifo mkfifo script2.fifo bzcat data*bz2 | tee script1.fifo script2.fifo perl script1.pl script1.fifo perl script2.pl script2.fifo ??? What about more than two scripts concurrently? What about n scripts? John McKown Systems Engineer IV IT -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: BASH question - may even be advanced - pipe stdout to 2 or more processes.
tee can output to multiple files? The man page implies only a single file. So I guess I could: bzcat data*bz2| tee (perl script1.pl|psql database)|perl script2.pl|psql database bzcat data*bz2| tee (perl script1.pl|psql database)|tee (pers script2.pl|psql database)|perl script3.pl|psql databaselin for the 2 case. I also guess that I might be able to cascade tee processes. But that's getting nasty, too. -- John McKown Systems Engineer IV IT Administrative Services Group HealthMarkets(r) 9151 Boulevard 26 * N. Richland Hills * TX 76010 (817) 255-3225 phone * john.mck...@healthmarkets.com * www.HealthMarkets.com Confidentiality Notice: This e-mail message may contain confidential or proprietary information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. HealthMarkets(r) is the brand name for products underwritten and issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake Life Insurance Company(r), Mid-West National Life Insurance Company of TennesseeSM and The MEGA Life and Health Insurance Company.SM -Original Message- From: Larry Ploetz [mailto:la...@stanford.edu] Sent: Wednesday, February 09, 2011 2:31 PM To: Linux on 390 Port Cc: McKown, John Subject: Re: BASH question - may even be advanced - pipe stdout to 2 or more processes. If you have a new enough bash, you can: bzcat data*bz2 | tee (process1) (process2) (process3) ... | processn but the stdout from process1..n get intermixed unless redirected to files. (Tom Meyer taught me that!) - Larry On 2/9/11 12:19 PM, McKown, John wrote: Yeah, it sound weird. What I have is 72 files containing a lot of secuity data from our z/OS RACF system. To save space, all these files are bzip2'ed - each individually. I am writing some Perl scripts to process this data. The Perl script basically reformats the data in such a way that I can put it easily into a PostgreSQL database. If I want to run each Perl script individually, it is simple: bzcat data*bz2 | perl script1.pl | psql database bzcat data*bz2 | perl script2.pl | psql database and so on. I don't want to try to merge the scripts together into a single, complicated, script. I like what I have in that regard. But I don't like running the bzcat twice to feed into each Pel script. Is something like the following possible? mkfifo script1.fifo mkfifo script2.fifo bzcat data*bz2 | tee script1.fifo script2.fifo perl script1.pl script1.fifo perl script2.pl script2.fifo ??? What about more than two scripts concurrently? What about n scripts? John McKown Systems Engineer IV IT -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: BASH question - may even be advanced - pipe stdout to 2 or more processes.
On 2/9/11 12:40 PM, McKown, John wrote: tee can output to multiple files? The man page implies only a single file. Hmmm...maybe you need a new enough tee also: SYNOPSIS tee [OPTION]... [FILE]... DESCRIPTION Copy standard input to each FILE, and also to standard output. So I guess I could: bzcat data*bz2| tee (perl script1.pl|psql database)|perl script2.pl|psql database bzcat data*bz2| tee (perl script1.pl|psql database)|tee (pers script2.pl|psql database)|perl script3.pl|psql databaselin Yep, those should work also. The named pipe would work too, if you did something like: mkfifo p1 p2 p3 bzcat data*bz2 | tee p1 | tee p2 p3 perl script1.pl p1 perl script2.pl p2 perl script3.pl p3 (make sure and background or run in another terminal the bzcat.) for the 2 case. I also guess that I might be able to cascade tee processes. But that's getting nasty, too. -- John McKown Systems Engineer IV IT - Larry -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: BASH question - may even be advanced - pipe stdout to 2 or more processes.
On Wednesday, February 09, 2011 03:19:03 pm you wrote:
Yeah, it sound weird. What I have is 72 files containing a lot of secuity
data from our z/OS RACF system. To save space, all these files are
bzip2'ed - each individually. I am writing some Perl scripts to process
this data. The Perl script basically reformats the data in such a way that
I can put it easily into a PostgreSQL database. If I want to run each Perl
script individually, it is simple:
bzcat data*bz2 | perl script1.pl | psql database
bzcat data*bz2 | perl script2.pl | psql database
and so on. I don't want to try to merge the scripts together into a single,
complicated, script. I like what I have in that regard. But I don't like
running the bzcat twice to feed into each Pel script. Is something like
the following possible?
mkfifo script1.fifo
mkfifo script2.fifo
bzcat data*bz2 | tee script1.fifo script2.fifo
perl script1.pl script1.fifo
perl script2.pl script2.fifo
???
What about more than two scripts concurrently? What about n scripts?
Using tee is the right approach, and the above should work OK. Solving this
problem for N outputs is a bit trickier, because you have to have something
that copies its input N times. That could be done with a shell loop. Here's
a function that copies its stdin to each of the files named on its command
line:
Ntee() {
while read line; do
for file; do
echo $line $file
done
done
}
Well, that does it, but it is opening each file and seeking to its end for
each line of input, and that's pretty inefficient. What we'd like to do is
keep the files open. Something like this might do it, but I haven't tested
it:
Ntee() {
fd=3
for file; do
eval $fd'$file'
fd=$((fd + 1))
done
while read line; do
fd=3
for file; do
eval 'echo $line 1'$fd
fd=$((fd + 1))
done
done
}
The first for-loop opens all the files and assigns file descriptors to them,
and the second for-loop writes to those open file descriptors. The eval is
used to expand the $fd (the rest of the command is protected from evaluation
be single-quotes) because the file-redirection syntax requires a number. So,
for example, the first time around the first loop, the command:
3$file
is what gets executed.
I haven't tried to run this, but the idea might help.
- MacK.
-
Edmund R. MacKenty
Software Architect
Rocket Software
275 Grove Street - Newton, MA 02466-2272 - USA
Tel: +1.617.614.4321
Email: m...@rs.com
Web: www.rocketsoftware.com
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Re: BASH question - may even be advanced - pipe stdout to 2 or more processes.
No, it's me. I didn't interpret [FILE]... as more than one file. My bad. I think this will handle what I want to do. Many thanks! -- John McKown Systems Engineer IV IT Administrative Services Group HealthMarkets(r) 9151 Boulevard 26 * N. Richland Hills * TX 76010 (817) 255-3225 phone * john.mck...@healthmarkets.com * www.HealthMarkets.com Confidentiality Notice: This e-mail message may contain confidential or proprietary information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. HealthMarkets(r) is the brand name for products underwritten and issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake Life Insurance Company(r), Mid-West National Life Insurance Company of TennesseeSM and The MEGA Life and Health Insurance Company.SM -Original Message- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Larry Ploetz Sent: Wednesday, February 09, 2011 2:48 PM To: LINUX-390@VM.MARIST.EDU Subject: Re: BASH question - may even be advanced - pipe stdout to 2 or more processes. On 2/9/11 12:40 PM, McKown, John wrote: tee can output to multiple files? The man page implies only a single file. Hmmm...maybe you need a new enough tee also: SYNOPSIS tee [OPTION]... [FILE]... DESCRIPTION Copy standard input to each FILE, and also to standard output. So I guess I could: bzcat data*bz2| tee (perl script1.pl|psql database)|perl script2.pl|psql database bzcat data*bz2| tee (perl script1.pl|psql database)|tee (pers script2.pl|psql database)|perl script3.pl|psql databaselin Yep, those should work also. The named pipe would work too, if you did something like: mkfifo p1 p2 p3 bzcat data*bz2 | tee p1 | tee p2 p3 perl script1.pl p1 perl script2.pl p2 perl script3.pl p3 (make sure and background or run in another terminal the bzcat.) for the 2 case. I also guess that I might be able to cascade tee processes. But that's getting nasty, too. -- John McKown Systems Engineer IV IT - Larry -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/ -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: BASH question - may even be advanced - pipe stdout to 2 or more processes.
On Wednesday, February 09, 2011 03:47:38 pm you wrote:
On 2/9/11 12:40 PM, McKown, John wrote:
tee can output to multiple files? The man page implies only a single
file.
Hmmm...maybe you need a new enough tee also:
SYNOPSIS
tee [OPTION]... [FILE]...
DESCRIPTION
Copy standard input to each FILE, and also to standard output.
Doh! I should have remembered that. So the functions I wrote could have been
implemented as:
Ntee() {
tee $@ /dev/null
}
Just goes to show that there's usually several ways to do anything in Linux.
I focused on doing it entirely in bash.
- MacK.
-
Edmund R. MacKenty
Software Architect
Rocket Software
275 Grove Street - Newton, MA 02466-2272 - USA
Tel: +1.617.614.4321
Email: m...@rs.com
Web: www.rocketsoftware.com
--
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send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit
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Re: BASH question - may even be advanced - pipe stdout to 2 or more processes.
On 2/9/11 1:08 PM, Edmund R. MacKenty wrote:
Doh! I should have remembered that. So the functions I wrote could have been
implemented as:
Ntee() {
tee $@ /dev/null
}
Just goes to show that there's usually several ways to do anything in Linux.
I focused on doing it entirely in bash.
- MacK.
Which is vaguely related to the perl mentality of never making a system call
and always finding
and using, or writing your own, module (that also doesn't make a system call).
I'm sure perl has
tee-like functions (actually, I remember a perl script named tee2 that did
write to multiple
output files), versus the more traditional (?) unix mentality of using many
small,
does-one-function-and-does-it-well utilities available in the environment, tied
together perhaps
with a shell script. I prefer the latter, but I can understand the portability
issues and the
perl-only solution to them.
- Larry
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Re: bash question.
John McKown wrote: Is there any better way, in a bash script, to pipe both stdout and stderr from an application other than using a subshell? So far the only way that I've thought of to do it is: (command parm1 ... 21) | othercommand The parentheses don't do anything useful. Here, stderr is discarded (by cat) in the first example, but not the second. 01:46 [sum...@numbat ~]$ find ~ -size +400c 21 | cat /dev/null 01:47 [sum...@numbat ~]$ find ~ -size +400c | cat /dev/null find: /home/summer/newstocks: Permission denied find: /home/summer/mystocks: Permission denied find: /home/summer/stocks: Permission denied 01:47 [sum...@numbat ~]$ -- Cheers John -- spambait 1...@coco.merseine.nu z1...@coco.merseine.nu -- Advice http://webfoot.com/advice/email.top.php http://www.catb.org/~esr/faqs/smart-questions.html http://support.microsoft.com/kb/555375 You cannot reply off-list:-) -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
bash question.
Is there any better way, in a bash script, to pipe both stdout and stderr from an application other than using a subshell? So far the only way that I've thought of to do it is: (command parm1 ... 21) | othercommand -- Q: What do theoretical physicists drink beer from? A: Ein Stein. Maranatha! John McKown -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
Re: bash question.
On 1/8/2009 at 12:36 PM, John McKown joa...@swbell.net wrote: Is there any better way, in a bash script, to pipe both stdout and stderr from an application other than using a subshell? So far the only way that I've thought of to do it is: (command parm1 ... 21) | othercommand Just: command parm1 21 | othercommand should work. If it doesn't for you, can you provide a specific example? Mark Post -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
Re: bash question.
On Thu, 8 Jan 2009, Mark Post wrote: On 1/8/2009 at 12:36 PM, John McKown joa...@swbell.net wrote: Is there any better way, in a bash script, to pipe both stdout and stderr from an application other than using a subshell? So far the only way that I've thought of to do it is: (command parm1 ... 21) | othercommand Just: command parm1 21 | othercommand should work. If it doesn't for you, can you provide a specific example? Mark Post Well, shoot. That never even occurred to me. What I thought that would do was: Change stderr to go where stdout currently goes, then change stdout to go into the pipe. I based this on the fact that if I do: command 21 1x.tmp Then stderr still comes to my terminal. It does not go to x.tmp. I guess there is some special code in bash to recognize the redirection piping as special. -- Q: What do theoretical physicists drink beer from? A: Ein Stein. Maranatha! John McKown -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
Re: bash question.
On Thursday 08 January 2009 14:13, John McKown wrote: Well, shoot. That never even occurred to me. What I thought that would do was: Change stderr to go where stdout currently goes, then change stdout to go into the pipe. I based this on the fact that if I do: command 21 1x.tmp Then stderr still comes to my terminal. It does not go to x.tmp. I guess there is some special code in bash to recognize the redirection piping as special. Actually, there's no special case for this. The rule is that the shell processes I/O redirections left-to-right. The 21 syntax just means make file descriptor 2 (stderr) refer to whatever file descriptor 1 (stdout) refers to. It doesn't change stdout at all. File descriptor 1 already refers to the pipe because the shell creates the pipes as it is parsing the pipeline, before it parses the simple commands within the pipeline. I hope that makes sense! :-) - MacK. - Edmund R. MacKenty Software Architect Rocket Software 275 Grove Street · Newton, MA 02466-2272 · USA Tel: +1.617.614.4321 Email: m...@rs.com Web: www.rocketsoftware.com -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
Re: bash question.
Thus, if you want the behaviour you described in the above command, you could do the following: command parms 21 | cat file.tmp which would put everything in the file file.tmp Erik Johnson On Thu, Jan 8, 2009 at 1:30 PM, Edmund R. MacKenty ed.macke...@rocketsoftware.com wrote: On Thursday 08 January 2009 14:13, John McKown wrote: Well, shoot. That never even occurred to me. What I thought that would do was: Change stderr to go where stdout currently goes, then change stdout to go into the pipe. I based this on the fact that if I do: command 21 1x.tmp Then stderr still comes to my terminal. It does not go to x.tmp. I guess there is some special code in bash to recognize the redirection piping as special. Actually, there's no special case for this. The rule is that the shell processes I/O redirections left-to-right. The 21 syntax just means make file descriptor 2 (stderr) refer to whatever file descriptor 1 (stdout) refers to. It doesn't change stdout at all. File descriptor 1 already refers to the pipe because the shell creates the pipes as it is parsing the pipeline, before it parses the simple commands within the pipeline. I hope that makes sense! :-) - MacK. - Edmund R. MacKenty Software Architect Rocket Software 275 Grove Street · Newton, MA 02466-2272 · USA Tel: +1.617.614.4321 Email: m...@rs.com Web: www.rocketsoftware.com -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
Re: bash question.
On 1/8/09 9:36 AM, John McKown wrote: Is there any better way, in a bash script, to pipe both stdout and stderr from an application other than using a subshell? So far the only way that I've thought of to do it is: (command parm1 ... 21) | othercommand Others have answered the question, but in case you want to know -- the technique (not the syntax!) you're using with the subshell is required in csh and derivative shells (e.g., tcsh). From the tcsh man page: The shell cannot presently redirect diagnostic output without also redirecting standard output, but `(command output-file) error- file' is often an acceptable workaround. Either output-file or error- file may be `/dev/tty' to send output to the terminal. You may have picked up the habit from too much exposure to Solaris? ;-) - Larry -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
Re: bash question.
On Thu, 8 Jan 2009, Edmund R. MacKenty wrote: On Thursday 08 January 2009 14:13, John McKown wrote: Well, shoot. That never even occurred to me. What I thought that would do was: Change stderr to go where stdout currently goes, then change stdout to go into the pipe. I based this on the fact that if I do: command 21 1x.tmp Then stderr still comes to my terminal. It does not go to x.tmp. I guess there is some special code in bash to recognize the redirection piping as special. Actually, there's no special case for this. The rule is that the shell processes I/O redirections left-to-right. The 21 syntax just means make file descriptor 2 (stderr) refer to whatever file descriptor 1 (stdout) refers to. It doesn't change stdout at all. File descriptor 1 already refers to the pipe because the shell creates the pipes as it is parsing the pipeline, before it parses the simple commands within the pipeline. I hope that makes sense! :-) - MacK. Ah! The little light goes on. That makes perfect sense. I was simply parsing the command from left to right, so that the redirection happened before the pipe, in my mind. -- Q: What do theoretical physicists drink beer from? A: Ein Stein. Maranatha! John McKown -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
