Date: Thu, 16 May 2013 16:27:53 +0000 From: "Teske, Devin" <Devin.Teske@fisglobal.com> To: Devin Teske <dteske@freebsd.org> Cc: Tim Daneliuk <tundra@tundraware.com>, FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: check variable content size in sh script Message-ID: <13CA24D6AB415D428143D44749F57D7201F4D4C9@ltcfiswmsgmb26> In-Reply-To: <13CA24D6AB415D428143D44749F57D7201F4D41F@ltcfiswmsgmb26> References: <5194F65F.6080503@a1poweruser.com> <5194FB0A.9090400@tundraware.com> <13CA24D6AB415D428143D44749F57D7201F4D41F@ltcfiswmsgmb26>
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On May 16, 2013, at 9:06 AM, Teske, Devin wrote:
>=20
> On May 16, 2013, at 8:28 AM, Tim Daneliuk wrote:
>=20
>> On 05/16/2013 10:08 AM, Joe wrote:
>>> Hello
>>>=20
>>> Have script that has max size on content in a variable.
>>> How to code size less than 51 characters?
>>>=20
>>=20
>> FOO=3D"Some string you want to check length of"
>> FOOLEN=3D`echo $FOO | wc | awk '{print $3}'`
>>=20
>=20
> Uh, without forking to 2 separate programs=85
>=20
> FOOLEN=3D${#FOO}
>=20
>=20
>> You can then use $FOOLEN in a conditional.
>>=20
>=20
>=20
> However, if the OP wanted to actually truncate $FOO to 51 characters:
>=20
>=20
> NEWFOO=3D$( echo "$FOO" | awk -v max=3D51 '{print substr($0,0,max)}' )
>=20
>=20
> However, if you want to handle the case of $FOO containing newlines (and =
you want the newline to count toward the max), then this instead would do t=
he trick:
>=20
>=20
> NEWFOO=3D$( echo "$FOO" | awk -v max=3D51 '
> {
> len =3D length($0)
> max -=3D len
> print substr($0,0,(max > 0 ? len : max + len))
> if ( max < 0 ) exit
> max--
> }' )
>=20
For fun, I decided to expand on the solution I provided immediately above=
=85 turning it into a function that you might be a little more familiar wit=
h:
snprintf()
{
local __var_to_set=3D"$1" __size=3D"$2"
shift 2 # var_to_set/size
eval "$__var_to_set"=3D\$\( printf \"\$@\" \| awk -v max=3D\"\$__si=
ze\" \''
{
len =3D length($0)
max -=3D len
print substr($0,0,(max > 0 ? len : max + len))
if ( max < 0 ) exit
max--
}'\' \)
}
Example usage:
FOO=3D$( printf "abc\n123\n" )
snprintf NEWFOO 6 "%s" "$FOO"
echo "NEWFOO=3D[$NEWFOO] len=3D[${#NEWFOO}]"
Produces:
NEWFOO=3D[abc
12] len=3D[6]
Hopefully this should help some folks.
--=20
Devin
>=20
> $NEWFOO, even if multi-line, will be limited to 51-bytes (adjust max=3D51=
accordingly for other desired-lengths). Newlines are preserved.
>=20
> Last, but not least, if you want to be able to handle multi-line values b=
ut only want to return the first line up-to N bytes (using 51 as the OP use=
d):
>=20
>=20
> NEWFOO=3D$( echo "$FOO" | awk -v max=3D51 '{ print substr($0,0,max); exit=
}' )
>=20
>=20
> If $FOO had multiple lines, $NEWFOO will have only the first line (and it=
will be truncated to 51 bytes or less).
> --=20
> Devin
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