On 12/04/2014 01:39 PM, Paul Eggert wrote: > On 12/04/2014 10:41 AM, John Kendall wrote: >> echo "$FILE ===========================\c"| cut -c1-30 > > Since you're going to have to rewrite it anyway if you want it to be > portable, I suggest doing it this way: > > printf '%.30s' "$FILE ===========================" > > as it's a lot more efficient anyway.
Be careful; the POSIX specification of '%.30s' does NOT work well with multibyte characters; it is specified as: http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap05.html#tag_05 "precision Gives the minimum number of digits to appear for the d, o, i, u, x, or X conversion specifiers (the field is padded with leading zeros), the number of digits to appear after the radix character for the e and f conversion specifiers, the maximum number of significant digits for the g conversion specifier; or the maximum number of bytes to be written from a string in the s conversion specifier. The precision shall take the form of a <period> ( '.' ) followed by a decimal digit string; a null digit string is treated as zero." which means that it CAN and WILL corrupt output if the number of bytes written falls in the middle of a multi-byte character. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
signature.asc
Description: OpenPGP digital signature
