YJL

I apologize for the confusing title, if you are coming in for a real cat, which meows and often plays innocently cute when they are under one-year old¹, then this post has nothing to do with those devils who wear furs².

A “cat”-like command or code is running but without using “cat” command, it’s what this post is about.

A couple of weeks ago, I suddenly wondered how many ways I can cat a file without using cat. Is there a simple command which only open file and dump to standard output? If you think cat is a simple command, then please man cat to see what it can do.

Be honest, how many of you have ever run cat file1 file2? I did twice, and that is probably all I have ever done for concatenating files. Standard input? Never did once. “Concatenating,” that’s what cat is named after, not for printing out a file that simple. Go check out the manpage, -n, -T, or -v options, have you used them before? cat isn’t that simple at all.

Alright, off-topic a little long, back to the subject. So far, I got these:

# Pure lame, period.
echo "$(<filename)"
printf '%s' "$(<filename)"

# Or sed 's/grep/sed/'
grep '' filename
grep '' <filename

# _Awk_ward...
awk '{print $0}' filename

# Head is tail, tail is head, what is what?
head -n -0 filename
tail -n +0 filename

# Flip! Flip! Can we be dumber?
tac filename | tac
rev filename | rev

# The best one to me, but it could be disaster if you forget to type
# redirection < before filename.
tee <filename

# !@#$%^&* Serioius?
OLDIDS="$IFS"; IFS=$'\n'; while read line; do echo "$line"; done <filename; IFS="$OLDIFS"

# Pi... pie?
python -c 'import sys; f=open(sys.argv[1]); sys.stdout.write(f.read()); f.close()' filename
python -c 'import sys; sys.stdout.write(sys.stdin.read())' <filename

None of them are a good one. Any other ideas? or do you know if there is one common Linux command sits in my harddisk and it does just opening and printing?

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[1]	Once they reach certain age, it’s like butterfly, turning into beautiful creatures from ugly wobble worms. Just, for cat, it might be the other way around.

[2]	Actually, I like cat and I had a cat. He was a cutie, but I believe he often thought someone is going to murder him or someone owes him a million dollars. [2013-02-15T07:43:47Z: originally linked video was gone, I put up another one]