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Old 08-24-2005, 04:08 AM   #1
jonhewer
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shell scipting: append output of a command to a variable


hi

doing a little bit of shell scripting.....

it's possible to append the output of a command to a file:

eg. echo "hello" >> file

but is there an equivalent to append the output to a variable? (i'm building up a log message which i want to both write to a log file and email)

the only way i currently know how to do this is:

var=${var}`echo "hello"`

thanks for your help
jon
 
Old 08-24-2005, 04:41 AM   #2
slackie1000
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hi there,
Code:
var=`echo "Hello World"`
won't work?
regards
slackie1000
 
Old 08-24-2005, 04:48 AM   #3
jonhewer
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Quote:
Originally posted by slackie1000
hi there,
Code:
var=`echo "Hello World"`
won't work?
regards
slackie1000
works for me....
 
Old 08-24-2005, 05:31 AM   #4
slackie1000
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hi there,
so, if it works... what is your question?
i thought, you want to have the output of a command assigned to a variable.
regards,
slackie1000
 
Old 08-24-2005, 05:34 AM   #5
jonhewer
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i want to append the output to a variable, ie. keeping its existing value, and appending the new data

var=${var}`echo "hello"` will do it, but i was wondering whether there's a cleaner way using the >> operator maybe?
 
Old 08-24-2005, 06:04 AM   #6
theYinYeti
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I know two methods:
1/ You don't need a line break:
Code:
var="${var}$(/path/to/command params)"
2/ You need a line break:
Code:
var="$(echo "$var"; /path/to/command params)"
Yves.

Last edited by theYinYeti; 08-24-2005 at 06:07 AM.
 
Old 08-24-2005, 06:09 AM   #7
jonhewer
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thanks theYinYeti that second method is handy

is it possible to append the stderr of a command to a variable?
 
Old 08-24-2005, 06:33 AM   #8
theYinYeti
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Of course. Instead of writing:
/path/to/command params

you write:
/path/to/command params 2>&1
if you want both stdout and stderr,

/path/to/command params 2>&1 >/dev/null
if you only want stderr.

Yves.
 
Old 08-24-2005, 06:36 AM   #9
jonhewer
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ah of course, cheers
 
Old 08-24-2005, 06:41 AM   #10
slackie1000
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*slackie1000 hits his head in the wall and buys an english dictionary*
sorry mate...
my mistake..
regards,
slackie1000
 
Old 08-24-2005, 06:42 AM   #11
jonhewer
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lol, no worries
 
  


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