看起来printf的%T指令可以像GNU的date -d一样解析日期时间字符串

fname="my_filename"
typeset -u date=$(printf '%(%b%Y)T' 'last month')
newname="${fname}_${date}"
print -v newname
# => my_filename_APR2023

$ printf --man
NAME
  printf - write formatted output

SYNOPSIS
  printf [ options ] format [string ...]
...
    %T    Treat string as a date/time string and format it. The T can be preceded by (dformat),
          where dformat is a date format as defined by the date command.

这是：

$ print -v .sh.version
Version AJM 93u+ 2012-08-01