Also, the cat makes for faster testing. I tend to start out with e.g. head bigfile.1.txt | grep | awk | stuff and refine things, and when output looks rig

Also, the cat makes for faster testing. I tend to start out with e.g. head bigfile.1.txt | grep | awk | stuff and refine things, and when output looks right, it's a simple "Ctrl+A Meta+D cat RET" to run it on the full output. Or vice versa if I suddenly want to go back to testing part of bigfile (or exchange the cat for "grep something"). If I want to change that to "< bigfile.1.txt", I have to "Ctrl+A Meta+D < Meta+F Meta+F Meta+F Ctrl+D Ctrl+D" – the extra keypresses are to delete the first "|" symbol. And if I suddenly want to change it back to head or grep, I have to reinsert the | (also I often by habit do Meta+D instead of Ctrl+D at the beginning of the line, which doesn't work as intended if the first token is "<" instead of "cat"). Those useless cats are quite handy when doing a lot of shell work.