NAME¶

smslen — Calculate SMS message payload length

SYNOPSIS¶

DESCRIPTION¶

smslen calculates how many bytes of SMS payload are required for the given input text.

The algorithm first attempts to encode the input using GSM 03.38, which requires seven or 14 bits per character (depending on whether the character is an ``extension'' character). However only certain commonly-used characters are encodable in GSM 03.38, so if any unsupported characters are seen, the algorithm reverts to UTF-16 encoding for the entire message, thus requiring 16 bits per character.

The first form prints the number of bytes required to encode the input.

The -r form inverts the calcaulation, printing the number of input bytes that will fit under the given encoded length limit. The SMS payload limit is 140 bytes, so for example -r 140 will calculate how much of the input text can fit in a single SMS message.

The -t form performs the same calculation as the -r form but copies the input to the output, truncating it when the calculated limit number of encoded output bytes is reached.

OPTIONS¶

-i

Specify input character encoding. By default, UTF-8 is assumed.

-r limit

Output the number of input bytes that, when encoded in an SMS payload, will have a length at most limit.

-t limit

Copy the input to the output up until the encoded length would reach limit.

-h

Output usage message and exit.

EXIT STATUS¶

smslen exits zero normally, or 1 if an error occurs.

Possible errors include an invalid byte sequence in the input.

SEE ALSO¶

twimsg(1), twils(1), twirm(1), twiping(1), twilog(1).

Adventures in Unicode SMS, http://www.twilio.com/engineering/2012/11/08/adventures-in-unicode-sms.

Wikipedia: GSM 03.38, http://en.wikipedia.org/wiki/GSM_03.38.

AUTHOR¶

Archie L. Cobbs ⟨archie.cobbs@gmail.com⟩