Re: Shift and rotate in gawk

[J Naman]

Why not avoid all the complexity, rebuilding $0, etc.:
str = ""
for (i=2; i<=NF; i++)  { str = str $i OFS}
str = str $i   # no trailing OFS for last one
print str
# or $0 = str ... etc
}
PS: FS = .. OFS = ... IMHO belong in a BEGIN{} block
By the time you set them in your example, the FIRST record
uses the default FS and only the second and subsequent recs
use your custom FS.