Is it worth mentioning useless uses of cat in this day and age?
Of course once you use the 'cat' trick you then have to remember which comments require '-', '-f -' or something to that effect because whoever programmed them didn't think the primary use case was to work as a filter.
Pipes are one of Unix's most useful features and cat somefile | asequenceofusefulcommands is a shorthand that anybody should be able to use.
Thank you.
It reminds me of the idiom of putting "# -- coding: utf-8 --" at the top of Python 2.x files. Which is incredibly useful, but nobody remembers, and googles everytime.
This comes from the fact the first famous tutorials on Python where written by emacs users, and this editor recognizes this idiom.
But fun fact, the regex matching this line is "^[ \t\v]#.?coding[:=][ \t]*([-_.a-zA-Z0-9]+)" (see https://www.python.org/dev/peps/pep-0263/) and accepts many variations (including a vim format).
The simplest variation is the dumb "# coding: utf8", which is not only straightforward and easy to remember, but way less magical for anybody reading the code.
Bottom line, if you are stuck in 2.x, use "# coding: utf8".
Imagine if you look for something else, you have to point the cursor in the middle, right after grep and before the file. With cat |grep you press Arrow-up and Alt+Backspace and you are right where you want to be, ready to search for something else.
In scripts you can save the extra process though.
The shells were developed on keyboards that didn't have arrow keys and have affordances for them.
I doubt the later one.
The teletype was a printing terminal and the ADM3A was a “glass teletype” — essentially a printing terminal too.
It’s possinle to write a lot of good code this way
FWIW anyway Brian wouldn't have thought about those keys as the intended use of Readline would have been emacs keystrokes (emacs, or EMACS as it was in those days, had recently been ported to Unix by RMS).
Interestingly our 36-bit machines (PDP-10s and lispms) had arrow glyphs on their custom non-ASCII keyboards (KTV and space cadet) but they were for mathematical notation, not cursor movement!
I would find it okay without cat to start the next line with "grep newPattern " and then fetching the previous filename with alt-. (edit: or !$ of course, but alt-. is more practical) -- not saying it's necessarily always better, but knowing your shell better (and/or using a better one) is often a viable alternative to using another construct.
Also, than* (sorry)
I don't see how the rest is faster than using Arrow-Up and deleting the last word. It seems more complicated. The most important string is still in the middle.