On May 16, 2013, at 9:27 AM, Teske, Devin wrote:
On May 16, 2013, at 9:06 AM, Teske, Devin wrote:
On May 16, 2013, at 8:28 AM, Tim Daneliuk wrote:
On 05/16/2013 10:08 AM, Joe wrote:
Hello
Have script that has max size on content in a variable.
How to code size less than 51 characters?
FOO="Some string you want to check length of"
FOOLEN=`echo $FOO | wc | awk '{print $3}'`
Uh, without forking to 2 separate programs…
FOOLEN=${#FOO}
You can then use $FOOLEN in a conditional.
However, if the OP wanted to actually truncate $FOO to 51 characters:
NEWFOO=$( echo "$FOO" | awk -v max=51 '{print substr($0,0,max)}' )
However, if you want to handle the case of $FOO containing newlines (and you
want the newline to count toward the max), then this instead would do the trick:
NEWFOO=$( echo "$FOO" | awk -v max=51 '
{
len = length($0)
max -= len
print substr($0,0,(max > 0 ? len : max + len))
if ( max < 0 ) exit
max--
}' )
For fun, I decided to expand on the solution I provided immediately above…
turning it into a function that you might be a little more familiar with:
snprintf()
{
local __var_to_set="$1" __size="$2"
shift 2 # var_to_set/size
eval "$__var_to_set"=\$\( printf \"\$@\" \| awk -v max=\"\$__size\" \''
{
len = length($0)
max -= len
print substr($0,0,(max > 0 ? len : max + len))
if ( max < 0 ) exit
max--
}'\' \)
}
Example usage:
FOO=$( printf "abc\n123\n" )
snprintf NEWFOO 6 "%s" "$FOO"
echo "NEWFOO=[$NEWFOO] len=[${#NEWFOO}]"
Produces:
NEWFOO=[abc
12] len=[6]
Hopefully this should help some folks.
I figured I'd help as many folks as I can…
http://svnweb.freebsd.org/base?view=revision&revision=250701
Added it to my string processing library. Lots of other useful functions in
there.
--
Cheers,
Devin
$NEWFOO, even if multi-line, will be limited to 51-bytes (adjust max=51
accordingly for other desired-lengths). Newlines are preserved.
Last, but not least, if you want to be able to handle multi-line values but
only want to return the first line up-to N bytes (using 51 as the OP used):
NEWFOO=$( echo "$FOO" | awk -v max=51 '{ print substr($0,0,max); exit }' )
If $FOO had multiple lines, $NEWFOO will have only the first line (and it will
be truncated to 51 bytes or less).
--
Devin
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