join 3 files

mierdatuti · 01-05-2009, 12:36 PM

Hi,

I have 2 files, for example:

fileA

hello I'm
My name is
.....

file B

David and you?
Pepe, what it's
.......

And I would like to have:

file C

1#hello I'm#David and you?
2#My name is#Pepe, what it's
...............

Could you say me how do it in bash!?

Many thanks,!

repo · 01-05-2009, 12:47 PM

http://tldp.org/LDP/Bash-Beginners-Guide/html/

pixellany · 01-05-2009, 12:49 PM

Have you looked at the "join" command?

You may also need SED to insert the "#" characters.

makyo · 01-06-2009, 09:53 AM

Hi.

One could probably do it all in bash, but I suggest paste as the main command, as in:

Code:

#!/bin/bash -

# @(#) s1       Demonstrate paste, awk.

echo
echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version "=o" $(_eat $0 $1) paste awk
set -o nounset
echo

FILE1=data1
FILE2=data2

echo " Data file $FILE1:"
cat $FILE1

echo
echo " Data file $FILE2:"
cat $FILE2

echo
echo " Results:"
paste -d'#' $FILE1 $FILE2 |
awk '{ print NR "#" $0 }'

exit 0

Producing:

Code:

$ ./s1

(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.11-x1, i686
Distribution        : Xandros Desktop 3.0.3 Business
GNU bash 2.05b.0
paste (coreutils) 5.2.1
GNU Awk 3.1.4

 Data file data1:
hello I'm
My name is

 Data file data2:
David and you?
Pepe, what it's

 Results:
1#hello I'm#David and you?
2#My name is#Pepe, what it's

matthewg42 · 01-06-2009, 10:19 AM

There are an almost unlimited number of ways to do this. Since you asked "in bash", here's a pure bash solution which doesn't rely on external programs at all. For almost all practical purposes this is not going to be the best method, but it's instructive about how the shell handles files.

Code:

#!/bin/bash

end=0
while [ $end -eq 0 ]; do
    Aend=0
    Bend=0
    read -u3 fileAline || Aend=1
    read -u4 fileBline || Bend=1
    if [ $Aend -eq 1 ] && [ $Bend -eq 1 ]; then
        end=1
    else
        echo "#$fileAline#$fileBline#"
    fi
done 3< fileA 4< fileB > fileC

Of course there are a great many variations of this. The version above is what spung to mind.

Specific things to note:

You can re-direct multiple files into a while loop using the "n<" syntax, where n is an integer file descriptor. 0, 1 and 2 are already used by the shell for stdin, stdout and stderr, so start your custom file descriptors at 3.
You can read some a numbered file descriptor using the -u option to the read command.
By putting || between two commands, the second one will only be executed if the return value of the first command is non-0. In the case of the read statements, read returns non-0 if the specified file descriptor is at the end of the file. This is documented in the bash manual page.

jiml8 · 01-06-2009, 11:13 AM

OP should at least thank the people here for doing his homework for him.

pixellany · 01-06-2009, 11:28 AM

Quote:

Originally Posted by jiml8

OP should at least thank the people here for doing his homework for him.

Posting history does not match the typical MO for a "homework troll".

Yes, he/she should thank us---and has in the past.

mierdatuti · 01-07-2009, 02:19 PM

Many thanks to all.