Re: using AWK
On Mon, 17 Dec 2012 08:16:26 -0800
Devin Teske wrote:
On Dec 17, 2012, at 3:39 AM, Jack Mc Lauren wrote:
Hi guys
How can I read a file which contains a number and assign that
number to a variable via awk programming? By the way, I want to use
this awk program in a shell script.
Thanks in advance
Try this:
awk -v file=/etc/ttys 'BEGIN { getline line file; printf First line
from %s: %s\n, file, line }'
Semms a bit complicated when you could set the awk variable directly
e.g.
$ echo 42 /tmp/f
$ awk -v x=`cat /tmp/f` 'BEGIN{ print x+1 }'
43
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Re: using AWK
Hi Jack, On Dec 17, 2012, at 03:39, Jack Mc Lauren jack.mclau...@yahoo.com wrote: How can I read a file which contains a number and assign that number to a variable via awk programming? By the way, I want to use this awk program in a shell script. I'm actually not sure what you're asking, exactly -- you want the number to go into an awk variable? Or a shell variable? Assuming you want it to go into an awk variable, I would try something like this: getline my_number filename; close filename; That assumes the filename is stored in the variable named filename. It puts the number in the awk variable named my_number. To put that in context, let's say you're getting the filename from $0, and you want to multiply the number by 2 and print it. You might do: filename = $0; getline my_number filename; close filename; print my_number * 2; Or if I completely misinterpreted your question, let me know :-) ~Ben ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: using AWK
On 12/17/2012 12:39 PM, Jack Mc Lauren wrote: Hi guys How can I read a file which contains a number and assign that number to a variable via awk programming? By the way, I want to use this awk program in a shell script. Thanks in advance ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org A good awk start : http://www.grymoire.com/Unix/Awk.html ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: using AWK
Hi Jack, HI How can I read a file which contains a number and assign that number to a variable via awk programming? By the way, I want to use this awk program in a shell script. I'm actually not sure what you're asking, exactly -- you want the number to go into an awk variable? Or a shell variable? Yes, I want the number to go into an awk variable. Assuming you want it to go into an awk variable, I would try something like this: getline my_number filename; close filename; That assumes the filename is stored in the variable named filename. It puts the number in the awk variable named my_number. To put that in context, let's say you're getting the filename from $0, and you want to multiply the number by 2 and print it. You might do: filename = $0; getline my_number filename; close filename; print my_number * 2; Or if I completely misinterpreted your question, let me know :-) ~Ben This is what i wrote: #! /bin/sh filename=$0 awk 'getline no filename; print no' But when I run this script sh /awk_no.sh /var/no.txt I have this error : awk: syntax error at source line 1 context is getline no filename; print no awk: bailing out at source line 1 Thank you :) ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: using AWK
On Mon, 17 Dec 2012 04:22:21 -0800 (PST), Jack Mc Lauren wrote:
Yes, I want the number to go into an awk variable.
[...]
This is what i wrote:
#! /bin/sh
filename=$0
awk 'getline no filename; print no'
But when I run this script
sh /awk_no.sh /var/no.txt
I have this error :
awk: syntax error at source line 1
context is
getline no filename; print no
awk: bailing out at source line 1
Thank you :)
The error is obvious: You need to transition $filename from
the sh level into the awk script, i. e. the file name string
(in your example, /var/no.txt) must be visible inside the
awk script. You're using a variable called filename which
is uninitialized (empty). You can either define the file
name statically in the awk script, or use ${filename} in
the script (use double quotes to allow resolution).
Also note that $0 is the name by which the script has been
called. $1 is the 1st parameter.
--
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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Re: using AWK
On Dec 17, 2012, at 04:22, Jack Mc Lauren jack.mclau...@yahoo.com wrote:
This is what i wrote:
OK -- I'm adjusting my assumptions about what you're trying to do. :-)
Bear with me:
#! /bin/sh
filename=$0
So (a) there's only one input file, not multiple... and (b) it should
come from the command line of the shell script wrapper. Right?
awk 'getline no filename; print no'
If there's only one input file, then this is super easy and you
don't even need any of the getline or close stuff. Try:
filename=$1
awk '{no = $0; print no;}' $filename
In the shell script context (outside the awk), $1 refers to the first
command line parameter of the script. You don't want $0 there.
On the other hand, *inside* the awk part, dollar-sign variables have
a completely different meaning. $0 in *awk* (not sh) means the entire
contents of each line of the input file. So if your file had multiple
lines, that block would run multiple times. But since I'm guessing your
file only has one line (that being the number in question), the awk
block will only run once.
~Ben
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Re: using AWK
On Dec 17, 2012, at 3:39 AM, Jack Mc Lauren wrote:
Hi guys
How can I read a file which contains a number and assign that number to a
variable via awk programming? By the way, I want to use this awk program in a
shell script.
Thanks in advance
Try this:
awk -v file=/etc/ttys 'BEGIN { getline line file; printf First line from %s:
%s\n, file, line }'
--
Devin
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Re: using AWK
On Mon, 17 Dec 2012 08:16:26 -0800, Devin Teske wrote:
On Dec 17, 2012, at 3:39 AM, Jack Mc Lauren wrote:
Hi guys
How can I read a file which contains a number and assign that number to a
variable via awk programming? By the way, I want to use this awk program in
a shell script.
Thanks in advance
Try this:
awk -v file=/etc/ttys 'BEGIN { getline line file; printf First line from
%s: %s\n, file, line }'
Or more verbose:
#!/bin/sh
filename=$1
echo file is ${filename} with content:
cat ${filename}
echo calling awk...
awk BEGIN {
getline no \${filename}\
close \${filename}\
print no
print no * 2
}
# EXAMPLE:
#
#
# % ./awkvar.sh /tmp/no.txt
# file is /tmp/no.txt with content:
# 12345
# calling awk...
# 12345
# 24690
The example shows how to use the variable inside awk. You
could get rid of the getline function in case the file
contains only the number you're interested in. If you need
further processing of the file, you can do that inside
awk (e. g. omitting comment lines, obtain data from a given
line number of specific pattern).
--
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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Re: using AWK
On Dec 17, 2012, at 8:23 AM, Polytropon wrote:
On Mon, 17 Dec 2012 08:16:26 -0800, Devin Teske wrote:
On Dec 17, 2012, at 3:39 AM, Jack Mc Lauren wrote:
Hi guys
How can I read a file which contains a number and assign that number to a
variable via awk programming? By the way, I want to use this awk program in
a shell script.
Thanks in advance
Try this:
awk -v file=/etc/ttys 'BEGIN { getline line file; printf First line from
%s: %s\n, file, line }'
Or more verbose:
#!/bin/sh
filename=$1
echo file is ${filename} with content:
cat ${filename}
echo calling awk...
awk -v filename=$filename BEGIN {
getline no filename
close filename
print no
print no * 2
}
# EXAMPLE:
#
#
# % ./awkvar.sh /tmp/no.txt
# file is /tmp/no.txt with content:
# 12345
# calling awk...
# 12345
# 24690
The example shows how to use the variable inside awk. You
could get rid of the getline function in case the file
contains only the number you're interested in. If you need
further processing of the file, you can do that inside
awk (e. g. omitting comment lines, obtain data from a given
line number of specific pattern).
--
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
_
The information contained in this message is proprietary and/or confidential.
If you are not the intended recipient, please: (i) delete the message and all
copies; (ii) do not disclose, distribute or use the message in any manner; and
(iii) notify the sender immediately. In addition, please be aware that any
message addressed to our domain is subject to archiving and review by persons
other than the intended recipient. Thank you.
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