Take the 2-minute tour ×
Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems.. It's 100% free, no registration required.

In another question I asked on how to hide all .pyc files when using ls, Ignacio suggested the following: ls | grep -v '.pyc$' | column

This, as I mentioned above, doesn't work precisely, since the output is occasionally misaligned:

ceasarbautista@hse140:~/Desktop/Statistics/statistics/markov$ ls
README          __init__.pyc        markov.py       matrix2graph.pyc    pathfinder.pyc      priority_dict.pyc   spanning.py
__init__.py     graph.py        matrix2graph.py     pathfinder.py       priority_dict.py    space.py        vector.py
ceasarbautista@hse140:~/Desktop/Statistics/statistics/markov$ ls | grep -v '\.pyc$' | column
README      graph.py        matrix2graph.py priority_dict.py    spanning.py
__init__.py markov.py   pathfinder.py   space.py        vector.py

While I got a satisfactory answer, I'm curious: why does column do this (and can it be fixed to print correctly)?

share|improve this question
What does shoving it through od -c say? –  Ignacio Vazquez-Abrams Oct 24 '11 at 2:48
gist.github.com/1308298 –  Ceasar Bautista Oct 24 '11 at 3:25
In the output shown above (and in your other post), even the ls output is misaligned. Perhaps it's something with your terminal. Trying adding | cat -A to the end of the pipeline, which will expose any hidden control or escape sequences that might be corrupting the output. –  James Sneeringer Oct 24 '11 at 4:52
So I don't have a -A (I'm using OS Lion if that matters), but presume -evt ought to do the same thing: gist.github.com/1308445 –  Ceasar Bautista Oct 24 '11 at 5:59
add comment

5 Answers

When called without any options, column makes each delimited strings align to the nearest TAB-STOP COLUMN. In a terminal, that is typically on every 8th character column.. Have a look at this example:

Create a file (ztxt) containing some tab-character \t delimited strings, spread over 3 lines which end with newline-character \n:


Output of: column ztxt - perfectly aligned to the nearest TAB-STOP

aaa1    aaaaaaaaaaaaaa2 aaaaaaaaaaaaaaaaaaa3    aaa4
bbbbbb1 bbb2    bbb3
ccc1    ccc2
|       |       |       |       |       |       |

To align the LSH of each successive field to the one above it, you need to use the -t option, eg. column -t ztxt

aaa1     aaaaaaaaaaaaaa2  aaaaaaaaaaaaaaaaaaa3  aaa4
bbbbbb1  bbb2             bbb3
ccc1     ccc2

If all your data is in one long stream without any newline breaks, you can uss a filter introduce them; eg one every 4 fields. sed can do it with this command.

sed -re 's/(([^\t]*\t){3}[^\t]*)\t/\1\n/g' 

By default, the column command will merge multiple adjacent delimiters into a single delimiter.. To cater for this in the sed filter, it also needs:

sed -re 's/\t+/\t/g;' 

So the command to split up a continuous stream of tab-delimited strings, as every 4th string is:

<ztxt sed -re 's/\t+/\t/g;s/(([^\t]*\t){3}[^\t]*)\t/\1\n/g' | column -t  

The output of such a contionuous input stream is (using the original sample input, but modified by replacing the original newlines with tab-characters--it must still keep its trailing \n):

aaa1      aaaaaaaaaaaaaa2  aaaaaaaaaaaaaaaaaaa3  aaa4
bbbbbbb1  bbb2             bbb3                  ccc1
share|improve this answer
add comment

If ls output is garbled, it indicates that there are non-printable characters within one or more filenames. I therefore recommend always to use the option -q with ls.

Any non-printable characters will then be printed out as a question mark.

So please try:

 ls -Cq
share|improve this answer
add comment

The problem with column is that it splits on \s+, I don't see how to make it split on a single tab. I wrote this much more flexible script to solve this problem, that anybody is free to use:


Here's the full usage:

 | This script displays tab delimited text in properly aligned columns.     |
 |                                                                          |
 | Usage: perl display.pl  [num lines] [options]                      |
 |                                                                          |
 | Where  is tab delimited.                                           |
 |                                                                          |
 | If  is followed by a positive integer N, only the first N lines    |
 | will be returned.                                                        |
 |                                                                          |
 | If lines are long, this script works bests if piped to "less -S".        |
 |                                                                          |
 | [options]                                                                |
 |                                                                          |
 | -noheader :  A header line is assumed by default.                        |
 |                                                                          |
 | -nodots   :  By default if a column is wide and an entry in that column  |
 |              is short, dots are put after it to help line things up.     |
 |              Use this option to just print spaces, no dots.              |
 |                                                                          |
 | -dotcols  :  Use this to specify specific columns to have dots     |
 |                    (see the -nodots option).   must be a comma     |
 |                    separated list of positive integers w/o whitespace.   |
 |                                                                          |
 | -cols  :  Use this to specify a subset of columns to output.       |
 |                  is a comma separated list of positive integers    |
 |                 and/or spans of positive integers.  Examples of valid    |
 |                 lists are: 4,6,12 or 4-10 or 1-4,12,15,4-7.  Columns     |
 |                 can be repeated and don't have to be in numerical order. |
 |                                                                          |
 | NOTE: This script was hacked from a much more complicated script, so     |
 | the code is full of all kinds of irrelevant stuff.                       |
share|improve this answer
add comment

To show non-printable characters (as C escape codes whenever possible) in your ls output you also can use the -b option to the ls command:

ls -Cb | grep -v '\.pyc$' | column -t
share|improve this answer
add comment

For the multiple delimiters bit. Annoyingly the -n option is only available in Debian, which handled multiple delimiters.

column -t -n <file>
share|improve this answer
add comment

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.