syms
====

`syms' lists symbols in its input (where "symbol" can be defined flexibly enough to be words, identifiers or XML tags).

unique symbols, sorted lexically: syms "$@" | sort | uniq
number of unique symbols: syms "$@" | sort | uniq | wc -l
unique symbols, sorted by frequency: syms "$@" | sort | uniq -c | sort -n -k 2
unique lines (like uniq, but not just adjacent lines): syms -s "^(.*)$" "$@"