cat is misunderstood a lot. The purpose of cat is to combine multiple files together (it's literally short for "concatenate"), like cat *.log to combine all log files together.

If you're just using it for a single file, then you should just redirect the file to stdin. These two command lines behave similarly:

cat foo.txt | some-command

some-command < foo.txt

For head, tail, grep and some other commands, you can just pass in the file name directly as an argument (e.g. grep whatever foo.txt).

[–] pedz@lemmy.ca 60 points 20 hours ago (1 children)

Also known as cat abuse.

[–] shark_byte@lemmy.zip 14 points 20 hours ago (2 children)

awww what's a cat without a head and a tail?

[–] ranzispa@mander.xyz 5 points 15 hours ago

I guess depending on your interpretation of without it could either be "cat" or "a".

[–] MonkderVierte@lemmy.zip 9 points 20 hours ago (1 children)

A kernel?

[–] shark_byte@lemmy.zip 5 points 20 hours ago

uhmm no

[–] ranzispa@mander.xyz 10 points 15 hours ago (1 children)

Fair, but in general I find it way more useful to use cat for piping.

In most cases I'll do something like

cat file | program
cat file | program | grep
cat file | program | grep | cut

This gets more complicated if the file is at the end of the command.

[–] dan@upvote.au 8 points 14 hours ago (1 children)

It wouldn't be at the end, since you'd still be piping into program

program <file | grep | cut

[–] jxk@sh.itjust.works 11 points 14 hours ago (2 children)

And <file program | grep | cut works too

[–] dan@upvote.au 1 points 10 hours ago

Thanks - I didn't know this either!

[–] ranzispa@mander.xyz 3 points 13 hours ago

Oh, thanks! Didn't know that

[–] qqq@lemmy.world 13 points 16 hours ago (1 children)

You'll see cat FILE | all the time because it's just a natural start to a pipeline. You cat FILE to see the content unfiltered before filtering it with further commands.

[–] BasedMaquisEddington@lemmy.dbzer0.com 10 points 13 hours ago

it’s just a natural start to a pipeline

[–] eager_eagle@lemmy.world 9 points 15 hours ago (1 children)

I still like doing cat file.txt | grep thing because I often re-run it to find something else like cat file.txt | grep thing2 - and if I do that with grep, the pattern sits awkwardly in the middle instead of at the end

[–] tgt@programming.dev 8 points 15 hours ago (1 children)

< file.txt grep thing also works.

[–] sqw@lemmy.sdf.org 0 points 56 minutes ago

is it more obtuse

[–] lokalhorst@feddit.org 14 points 20 hours ago* (last edited 19 hours ago) (3 children)

If I just want to look at the file, is there a better way than cat foo.txt? I guess I can't just do < foo.txt

[–] dan@upvote.au 9 points 14 hours ago* (last edited 6 hours ago) (1 children)

Admittedly I still use cat for this.

This also works too, but it's more verbose:

echo "$(<foo.txt)"

It's mentioned in the Bash man pages:

The command substitution $(cat file) can be replaced by the equivalent but faster $(< file).

EDIT: I was just informed that simply <foo.txt works too.

[–] not_IO@lemmy.blahaj.zone 1 points 7 hours ago (1 children)

how in the world is this not a useless use of echo and equivalent to <foo.txt

[–] dan@upvote.au 2 points 6 hours ago

OK, TIL you can just do <foo.txt. I didn't think that worked. Thanks!

[–] TwilightKiddy@scribe.disroot.org 1 points 9 hours ago

You can use less. There are also specialized ones for that purpose like bat.

[–] mote@lemmy.ca 18 points 19 hours ago

So close! you have to do cat < foo.txt :-) (/s)

[–] shark_byte@lemmy.zip 14 points 21 hours ago (1 children)

yeah sure but the command is literally written for the humor.

[–] dan@upvote.au 15 points 20 hours ago (2 children)

I know, but I just wanted to mention this since a lot of new Linux users end up using cat this way :)

[–] Grail@multiverse.soulism.net 3 points 13 hours ago (1 children)

Is there any downside?

[–] shark_byte@lemmy.zip 4 points 20 hours ago (1 children)

ohhh but it's all humor that's the point of the post.

I mean as a new Linux user, I won't take anything from a humor group seriously.

[–] daychilde@lemmy.world 1 points 4 hours ago

I would.

I'd be careful of jokes, sure, but geeks often can't help have real discussions. Like in this very thread