CODEWITHSUNDEEP
unixawksedaixed
René Alejandro Santiago
René Alejandro Santiago

Reputation: 145

Adding Text using ed to the End of a Specific Line within a File

I have two files, both contain tens of thousands of lines. I'm currently taking a string (Z1234562) from file_one.txt and trying to see if its on file_two.txt. If it's found on file_two.txt, I'm returning the line number the match was on -- in this case, line 1235. I have this working already.

file_one.txt
Line 1> [...]_Z1234562

file_two.txt
Line 1234> [...],Z1234561,[...]
Line 1235> [...],Z1234562,[...]
Line 1236> [...],Z1234563,[...]

However, I want to now append to line 1235 the string ,Yes. So that on file_two.txt I have

Line 1235> [...],Z1234562,[...],Yes

With the help Glenn Jackman's answer of this other question I was able to figure out how to add text using the ed editor before and after a specific line within a file. However, I haven't been able to figure out if with ed I can add text to the end of a line within a file. Reading the documentation I'm not sure there is. So far, based off this AIX site, this is what I have:

(echo '15022a'; echo 'Text to add.'; echo '.'; echo 'w'; echo 'q') | ed -s filename.txt

This appends the string Text to add. after line 15,022. I'm wondering if there is an insert equivalent to this append.

The reason I'm not using sed is because I'm on an AIX system and I can't seem to get what this forum has working. However, I'm not sure if the sed command in this forum only solves adding text before or after a line and not at the end of the line, which I already have working.

My next approach is to remove the return character at the end of the line I want to append to, append, and then re-add the return character but I don't want to reinvent the wheel before exhausting my options. Maybe I'm missing something as I want to do this as soon as possible but any help would be appreciated. I'm starting not to like these AIX systems. Maybe awk can help me but I'm less familiar with awk.

I wrote a small binary search subroutine using Perl in order to find the line that I want to append to. I'm not sure if sed, ed, grep, awk, etc. use binary search but that's why I'm not using ed or sed's pattern-replace searches. I want it to be as fast as possible so I'm open to a different approach.

Upvotes: 2

Views: 3092

Answers (3)

Adam
Adam

Reputation: 18807

You can use the j command

(.,.+1)j Joins the addressed lines. The addressed lines are deleted from the buffer and replaced by a single line containing their joined text. The current address is set to the resultant line.

So you just have to modifiy your previous command :

cat << EOF | ed -s filename.txt
15022a
Text to add.
.
-1,.j
wq
EOF

Upvotes: 2

James Brown
James Brown

Reputation: 37394

First we create a test file foo:

$ cat > foo
foo
bar

If you already know the line number you want to edit, e.g. previous example and line number 2 using sed:

$ sed '2s/$/foo' foo
foo
barfoo

In awk you'd command:

$ awk 'NR==2 {sub(/$/,"foo")} 1' foo
foo
barfoo

In perl:

$ perl -p -e 's/$/foo/ if $. == 2' foo
foo
barfoo

Upvotes: 0

Steve Summit
Steve Summit

Reputation: 47923

Here is a general recipe I have used for invoking ed from a script:

(echo '/pattern/s/$/ new text/'
 echo w ) | ed filename

This invokes ed on filename, searches for a line containing pattern, and appends "new text" at the end of that line. Season to taste.

You said you were having trouble with sed, but for the record, here's the same sort of thing using sed:

sed '/pattern/s/$/ new text/' filename > filename.modified

Upvotes: 3

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