Replacing values into a single column. sed/PERL

Shell Programming and Scripting
1

Hello everyone,
i need to replace in the second column of my csv file, points by nothing and dash by comma like this:

Input:

1 2 1;12.111.312-2;1.2;2;1-3
2 1 1;11.212.331-1;3.3;1;2-2

Output:

1 2 1;12111312;2;1.2;2;1-3
2 1 1;11212331;1;3.3;1;2-2

SED or PERL commands preferably.

Thanks!

2

You said you wanted "-" in field 2 to be replaced by ","; but your sample output used ";" instead of ",". Which do you really want?

What have you tried?

Why are sed and perl preferable to awk for this?

3

in fact i want to replace "-" by semicolon instead simple comma (Mea culpa)
I prefer sed or perl because after some experiences i have seen that sed or perl commands was more fast than awk...

4

And, what have you tried?

5

I assume he doesn't know where to start :wink:

# accurate and fast (recommended)
awk -F";" '{gsub(/\./,"",$2); sub(/-/,";",$2); print}' OFS=";" input

# accurate, but relatively slow
perl -e 'while(<>){ @f=split(/;/); $f[1]=~s/\.//g; $f[1]=~s/-/;/; print join(";",@f); }' input

# very fast, but it doesn't care for columns, it simply deletes the first two occurrences of "."
# and replaces the first ocurrence of "-" with ";". It might work for you, if there are no "."s
# and no "-" in the first column PLUS if there are always two "."s and one "-" in the second column.
sed 's/\.//;s/\.//;s/-/;/' input
7

i cant select just the 2nd column. To replace its easy with

sed -i

command but i can do that for the whole file. To remove points, i can use

grep -Ev

, but how select just the 2nd column to do these changes.

Thanks

Julien

8

I prefer using awk (as suggested by junior-helper) because it is easy for me to read and immediately understand. I believe the following sed script also does what you want, but for many users this is less readable and harder to understand:

sed '
:again
/^\([^;]*;[^.;]*\)[.]/s//\1/
t again
/^\([^;]*;[^-;]*\)-/s//\1;/
' Input

Fast is nice; but I'm not sure that sed is going to be any faster than awk for this. Which script do you find easier to understand?

10

Depending on your shell version, you can use bash alone without calling external tools.

while IFS=";" read -r line; do
    set -- ${line}
    tmp=${2//./}
    echo "${line/$2/${tmp//-/$IFS}}"
done < inputfile

Due to the simplicity and trivial performance difference, I would still recommend using awk. Nice to have several approaches to chose from though :slight_smile: