Help using sed or awk for file edit

Posted on 2007-04-02
Last Modified: 2010-04-21
Can I ask for some help editting a file using sed or awk?

I have a pipe delimited file with 30 fields per record.

The 30th field contains numbers.

I want to find all the 12 digit numbers that start with a 7, and change them to eleven digit numbers.  Basically I need to remove the leading 7 from the 12 digit numbers so I am left with a 11 digit number in that field.
Question by:roone
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LVL 45

Expert Comment

by:Kent Olsen
ID: 18837937
Hello roone,

There are several ways to do this.  The easiest sed solution is to assume that the last field is being edited.

Change the ',' to the correct separator, if necessary.  This solution requires that there are no null fields (there are no consecutive separators).

sed 's/,7[0-9]\{11\}$/,&/; s/,,7/,/' myfile

Good Luck,

Author Comment

ID: 18838010
The records are separated by |

LVL 45

Expert Comment

by:Kent Olsen
ID: 18838033

Make sure to escape the '|' character.   :)

sed 's/\|7[0-9]\{11\}$/\|&/; s/\|\|7/\|/' myfile

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Author Comment

ID: 18838078
# cat testsed
s/|7[0-9]\{11\}$/|&/; s/||7/|/

I made this sed file.  I used it on a test file, and it just removed the numbers starting with 7.

Can you break down the actual expression for me?

I understand the first part "search for a pipe followed by a seven and then 11 other digits"
, right?

But I get lost after the $

Author Comment

ID: 18838087
Oh, wait.  There are consecutive separators.

But I am definately only touching the last field.

Can't I say, grab the 30th field and then do this substitution?


Author Comment

ID: 18838192
# cat trythis

This worked for me.


LVL 45

Accepted Solution

Kent Olsen earned 50 total points
ID: 18838703
Hi roone,

You can certainly grab the 30th something.  The script that I provided grabbed the last field, which happens to be the 30th.  :)

I don't know your data very well, but your script doesn't care where the 7........... entry is.  And will change ALL occurences, not just parameter 30.


Author Comment

ID: 18839151
Understood.  Thanks for the help.

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