concatenate ordered files using cat on Linux

Question

I have files from 1 to n, which look like the following:

sim.o500.1 
sim.o500.2
.
.
.
sim.o500.n

Each file contains only one line. Now I want to concatenate them in the order from 1 to n.

I tried cat sim.o500.* > out.dat. Sadly this does not work if e.g. n is larger than 9, because this concatenates then sim.o500.1 followed by sim.o500.10and not sim.o500.1 followed by sim.o500.2.

How can I loop through the file names using the numeric order?

Related: [What's the best way to join files after splitting?](http://unix.stackexchange.com/q/24630/30580) — legends2k, Apr 01 '15 at 15:07

fedorqui · Accepted Answer · 2015-04-01T15:17:44.690

2

Since * expands in a non-numeric-sorted way, you'd better create the sequence yourself with seq: this way, 10 will coome after 9, etc.

for id in $(seq $n)
do
   cat sim.o500.$id >> out.dat
done

Note I use seq so that you are able to use a variable to indicate the length of the sequence. If this value happens to be fixed and known beforehand, you can directly use range expansion writing the n value like: for id in {1..23}.

edited Apr 01 '15 at 15:17

answered Apr 01 '15 at 11:51

fedorqui

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I tried this for ten files, but this only concatenates the first and the tenth file. I used the loop condition `for id in {1,10}`. – nerdizzle Apr 01 '15 at 13:42
Ops! I mean `for id in {1..10}`. The other one was wrong, sorry. – fedorqui Apr 01 '15 at 14:18
Not at all! `{1,10}` is also fine, but just as enumeration of `1` and `10`. – fedorqui Apr 01 '15 at 14:40

score 2 · Answer 2 · edited May 23 '17 at 12:06

2

echo {1..12}

would print

1 2 3 4 5 6 7 8 9 10 11 12

You can use this Bash's range expansion feature to your advantage.

cat sim.o500.{1..20}

would expand to the filenames in numerically sorted order and it is terse (lesser keystrokes).

One caveat is that you may hit the "too many arguments" error if the file count exceeds the limit.

edited May 23 '17 at 12:06

Community

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answered Apr 01 '15 at 15:03

legends2k

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This is nice! I was mentioning range expansion in my answer but didn't think about doing it this way. Simple and nice, +1! – fedorqui Apr 01 '15 at 15:08
Thank you, I didn't know it actually, I got this tip from the _Related_ question commented under the question. In a sense, your's is better since it doesn't have the argument limit issue. – legends2k Apr 01 '15 at 15:11

GreenScape · Answer 3 · 2015-04-01T14:48:12.660

Try

ls sim.o500.* | sort -t "." -n -k 3,3 | xargs cat > out.dat

Explanation:

ls

ls sim.o500.* will produce a list of file names, matching pattern sim.o500.*, and pass it over the pipe to sort

sort

sort -t "." -n -k 3,3 will grab all those file names and sort them as numbers (-n) in descending order using 3rd column (-k 3,3) and pass it over the pipe to xargs.

-t "." tells sort to use . as a separator, instead of spacing characters, as it does by default. So, having sim.o500.5 as an example, the first column would be sim, the second column: o500 and the third column: 5.

xargs

xargs cat > out.dat will start cat and append all lines, received via pipe from sort as command arguments. It does something like:

execute("cat > out.dat sim.o500.1 sim.o500.2 sim.o500.3 ... sim.o500.n")

@nerdizzle, I've edited my answer in attempt to explain what's going on. — GreenScape, Apr 01 '15 at 14:48

score 0 · Answer 4 · answered Apr 01 '15 at 12:14

0

> out.dat
for i in `ls -v sim*`
do
echo $i
cat $i >> out.dat
done

answered Apr 01 '15 at 12:14

kjohri

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score 0 · Answer 5 · answered Oct 31 '16 at 11:33

0

If you have all the files in a folder try to use this command:

cat $(ls -- sim* | sort) >> out.dat

answered Oct 31 '16 at 11:33

Oibaf it

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concatenate ordered files using cat on Linux

5 Answers5