Ttyjfyk

I have the following two files ( I padded the lines with dots so every line in a file is the same width and made file1 all caps to make it more clear).

contents of file1:

ETIAM......
SED........
MAECENAS...
DONEC......
SUSPENDISSE

contents of file2

Lorem....
Proin....
Nunc.....
Quisque..
Aenean...
Nam......
Vivamus..
Curabitur
Nullam...

Notice that file2 is longer than file1.

When I run this command:

paste file1 file2

I get this output

ETIAM...... Lorem....
SED........ Proin....
MAECENAS... Nunc.....
DONEC...... Quisque..
SUSPENDISSE Aenean...
 Nam......
 Vivamus..
 Curabitur
 Nullam...

What can I do for the output to be as follows ?

ETIAM...... Lorem....
SED........ Proin....
MAECENAS... Nunc.....
DONEC...... Quisque..
SUSPENDISSE Aenean...
 Nam......
 Vivamus..
 Curabitur
 Nullam...

I tried

paste file1 file2 | column -t

but it does this:

ETIAM...... Lorem....
SED........ Proin....
MAECENAS... Nunc.....
DONEC...... Quisque..
SUSPENDISSE Aenean...
Nam......
Vivamus..
Curabitur
Nullam...

non as ugly as original output but wrong column-wise anyway.

Assuming you don't have any tab characters in your files,

paste file1 file2 | expand -t 13

with the arg to -t suitably chosen to cover the desired max line width in file1.

OP has added a more flexible solution:

I did this so it works without the magic number 13:

paste file1 file2 | expand -t $(( $(wc -L <file1) + 2 ))

It's not easy to type but can be used in a script.

I thought awk might do it nicely, so I googled "awk reading input from two files" and found an article on stackoverflow to use as a starting point.

First is the condensed version, then fully commented below that. This took a more than a few minutes to work out. I'd be glad of some refinements from smarter folks.

awk 'if(length($0)>max)max=length($0)
FNR==NRs1[FNR]=$0;nexts2[FNR]=$0
END format = "%-" max "st%-" max "sn";
 numlines=(NR-FNR)>FNR?NR-FNR:FNR;
 for (i=1; i<=numlines; i++) printf format, s1[i]?s1[i]:"", s2[i]?s2[i]:"" 
' file1 file2

And here is the fully documented version of the above.

# 2013-11-05 mike@diehn.net
# Invoke thus:
# awk -f this_file file1 file2
# The result is what you asked for and the columns will be
# determined by input file order.
#----------------------------------------------------------
# No matter which file we're reading,
# keep track of max line length for use
# in the printf format.
#
 if ( length($0) > max ) max=length($0) 

# FNR is record number in current file
# NR is record number over all
# while they are equal, we're reading the first file
# and we load the strings into array "s1"
# and then go to the "next" line in the file we're reading.
FNR==NR s1[FNR]=$0; next 

# and when they aren't, we're reading the
# second file and we put the strings into
# array s2
s2[FNR]=$0

# At the end, after all lines from both files have
# been read,
END 
 # use the max line length to create a printf format
 # the right widths
 format = "%-" max "st%-" max "sn"
 # and figure the number of array elements we need
 # to cycle through in a for loop.
 numlines=(NR-FNR)>FNR?NR-FNR:FNR;
 for (i=1; i<=numlines; i++) 
 printf format, s1[i]?s1[i]:"", s2[i]?s2[i]:""
 

Not a very good solution but I was able to do it using

paste file1 file2 | sed 's/^TAB/&&/'

where TAB is replaced with the tab character.

On Debian and derivatives, column has a -n nomerge option that allows column to do the right thing with empty fields. Internally, column uses the wcstok(wcs, delim, ptr) function, which splits a wide character string into tokens delimited by the wide characters in the delim argument.

wcstok starts by skipping wide characters in delim, before recognizing the token. The -n option uses an algorythm that doesn't skip initial wide-characters in delim.

Unfortunately, this isn't very portable: -n is Debian-specific, and column is not in POSIX, it's apparently a BSD thing.

Taking out the dots that you used for padding:

file1:

ETIAM
SED
MAECENAS
DONEC
SUSPENDISSE

file2:

Lorem
Proin
Nunc
Quisque
Aenean
Nam
Vivamus
Curabitur
Nullam

Try this:

$ ( echo ".TS"; echo "l l."; paste file1 file2; echo ".TE" ) | tbl | nroff | more

And you will get:

ETIAM Lorem
SED Proin
MAECENAS Nunc
DONEC Quisque
SUSPENDISSE Aenean
 Nam
 Vivamus
 Curabitur
 Nullam