Bash – list file names with sorted order – ls command

bashlsshellsortingunix

I have some files in a UNIX directory:

/opt/apps/testloc $ ls -mn 
test_1.txt
test_2.txt
test_11.txt
test_12.txt
test_3.txt

I want to list this with ls command and I need the output in sorted order based on the numbers at the end of the file name. Say output should be like below.

test_1.txt, test_2.txt, test_3.txt, test_11.txt, test_12.txt

I am not able to get as mentioned. These file names were considered as text and they were sorted as below,

test_11.txt, test_12.txt, test_1.txt, test_2.txt, test_3.txt

My command ls –mn (I need the output to be in comma separated format so I have used -m)

I need this to be done to process the files in incremental format in my next process.

Best Answer

If you version of sort can do a version sort with -V then:

$ ls | sort -V | awk '{str=str$0", "}END{sub(/, $/,"",str);print str}'
test_1.txt, test_2.txt, test_3.txt, test_11.txt, test_12.txt

If not do:

$ ls | sort -t_ -nk2,2 | awk '{str=str$0","}END{sub(/,$/,"",str);print str}'
test_1.txt, test_2.txt, test_3.txt, test_11.txt, test_12.txt

Related Solutions

Linux – How to write stderr to a file while using “tee” with a pipe

I'm assuming you want to still see STDERR and STDOUT on the terminal. You could go for Josh Kelley's answer, but I find keeping a tail around in the background which outputs your log file very hackish and cludgy. Notice how you need to keep an exra FD and do cleanup afterward by killing it and technically should be doing that in a trap '...' EXIT.

There is a better way to do this, and you've already discovered it: tee.

Only, instead of just using it for your stdout, have a tee for stdout and one for stderr. How will you accomplish this? Process substitution and file redirection:

command > >(tee -a stdout.log) 2> >(tee -a stderr.log >&2)

Let's split it up and explain:

> >(..)

>(...) (process substitution) creates a FIFO and lets tee listen on it. Then, it uses > (file redirection) to redirect the STDOUT of command to the FIFO that your first tee is listening on.

Same thing for the second:

2> >(tee -a stderr.log >&2)

We use process substitution again to make a tee process that reads from STDIN and dumps it into stderr.log. tee outputs its input back on STDOUT, but since its input is our STDERR, we want to redirect tee's STDOUT to our STDERR again. Then we use file redirection to redirect command's STDERR to the FIFO's input (tee's STDIN).

See http://mywiki.wooledge.org/BashGuide/InputAndOutput

Process substitution is one of those really lovely things you get as a bonus of choosing bash as your shell as opposed to sh (POSIX or Bourne).

In sh, you'd have to do things manually:

out="${TMPDIR:-/tmp}/out.$$" err="${TMPDIR:-/tmp}/err.$$"
mkfifo "$out" "$err"
trap 'rm "$out" "$err"' EXIT
tee -a stdout.log < "$out" &
tee -a stderr.log < "$err" >&2 &
command >"$out" 2>"$err"

Unix – How to reverse the order of lines in a file

Also worth mentioning: tac (the, ahem, reverse of cat). Part of coreutils.

Flipping one file into another

tac a.txt > b.txt

Best Answer

Related Solutions

Linux – How to write stderr to a file while using “tee” with a pipe

Unix – How to reverse the order of lines in a file

Flipping one file into another

Related Topic