[xubuntu-users] dash - looping through alphabet

[Ralf Mardorf]

On Sat, 2014-07-05 at 19:49 -0400, Steve Litt wrote:
> I couldn't get anything to work without putting spaces between every
> letter from a to z.

Thank you,

but if this is needed, then I don't want to use a loop, but do it this
way:

case $d in
      a*) 
        d=0;;
      b*)
        d=1;;
      c*)
        d=2;;
      d*)
        d=3;;
      [snip]

I will do a conversion from "a_foo" to "0", "b_foo" to "1"
etc.. /dev/sda to /dev/sdz should become a number [1]. I
ignore /dev/sdAa, /dev/sdAb etc..

>  Would you consider a C solution?

No, it should be a shell script and for this script I prefer dash over
bash, since the scrip should do several other operations, it should be
easy to modify it and it should be fast.

I tried another loop, but it also doesn't work.

$ cat while-dash 
i=97
while [ $i != 123 ]; do
  printf "\x$(printf %x $i)"
  i=$((i+1))
done
printf "\n"
exit

$ bash ./while-dash 
abcdefghijklmnopqrstuvwxyz
$ dash ./while-dash 
\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c\x6d\x6e\x6f\x70\x71\x72
\x73\x74\x75\x76\x77\x78\x79\x7a

Regards,
Ralf

[1]
    # [snip]
    # Transform label to hd device,partition
    root_p_devdp=$(blkid -L $root_p_label | cut -f3 -d"d")
    d=${root_p_devdp%%?}
    i=0
    for str in {a..z} ; do
    # [snip] it does work without a loop, by using "case"
    #case $d in
    #  a*) 
    #    d=0;;
    #  b*)
    #    d=1;;
    #  c*)
    #    d=2;;
    #  d*)
    #    d=3;;
    #  e*)
    #    d=4;;
    #  f*)
    #    d=5;;
    #  g*)
    #    d=6;;
    #  h*)
    #    d=7;;
    #  i*)
    #    d=8;;
    #  j*)
    #    d=9;;
    #  k*)
    #    d=10;;
    #  l*)
    #    d=11;;
    #  m*)
    #    d=12;;
    #  n*)
    #    d=13;;
    #  o*)
    #    d=14;;
    #  p*)
    #    d=15;;
    #  q*)
    #    d=16;;
    #  r*)
    #    d=17;;
    #  s*)
    #    d=18;;
    #  t*)
    #    d=19;;
    #  u*)
    #    d=20;;
    #  v*)
    #    d=21;;
    #  w*)
    #    d=22;;
    #  x*)
    #    d=23;;
    #  y*)
    #    d=24;;
    #  z*)
    #    d=25;;
    #   *) printf "\n$0: can't transform label\n"; exit 2;;
    #esac
    p=${root_p_devdp#*?}

    # [snip]
    printf "\n  set root='(hd$d,$p)'; set legacy_hdbias='0'"  
    # [snip]