as of 2013, the unix shell tool syntax have gone thru more evolution.
note, in 1990s, the GNU introduced the double-dash syntax. ⁖
diff --brief, in hope to make it readable. Unfortunately, it didn't really catch on. Most commands today do offer the double-dash variant, but only for some options. The double-dash option does not necessarily mean there's a corresponding single-dash one, and vice versa. What happened instead is just a new syntax variation.
during 2000s, a new syntax form became popular, one that has a “action” keyword immediately following the command name. Here are some prominent examples:
apt-get install --simulate -y ‹name›
git add -m"…" ‹fpath›
iptables --table filter --append INPUT --jump DROP
One good example of the confuse ball in one command can be seen in Linux's “ps” command. See
read more at: Unix Pipe as Functional Language