mjhjmtu

So, basically I have lines like these:

ILU1910ilu0001 “ My hand is broken , ” said the sailor , “ and smoked the pipe . ” 
ILU1910ilu0001 “ It is going make life harder for us , ” he said . 

And I want them to look like this:

<ignore>ILU1910ilu0001</ignore> “ My hand is broken , ” said the sailor , “ and smoked the pipe . ” 
<ignore>ILU1910ilu0001</ignore> “ It is going make life harder for us , ” he said . 

Basically at the start of each line there is ILU1910/ilu0001 and I want to add <ignore> at the start and </ignore> at the end of said phrase.

I tried to use this to make it work by using this command:

cat file.txt | sed 's/^([^A-Za-z0-9]+ )/<ignore>1</ignore>/g'

But it does not seem to work. I am using the terminal on my MacBook.

It is easily done using sed.

sed 's/ILU1910\ilu0001/<ignore>&</ignore>/' file.txt

Since there is only one pattern to match, you can do it more easily using &. If you want to use cat, it'll be

cat file.txt | sed 's/ILU1910\ilu0001/<ignore>&</ignore>/'

In your attempt, you are working with anything non-alphanumeric [^A-Za-z0-9]. You could modify your pattern to anything non-blank using [^ ]* as follows:

sed 's/^[^ ]*/<ignore>&</ignore>/' file.txt

If you're trying to edit a file in-place, you could script the changes with ed:

ed -s file.txt <<< $'1,$s,ILU1910\\ilu0001,<ignore>ILU1910\\ilu0001</ignore>,nwnq'

This calls ed in -s silent mode and sends it a list of instructions in a quoted here-string:

• 
  1,$s,ILU1910\\ilu0001,<ignore>ILU1910\\ilu0001</ignore>, - on every line (1,$), search and replace (s, ... , ... ,) the first part with the second part. Because there's a forward slash in the replacement text, I changed the typical / delimiter to a comma (,), since there were no commas in the search or replacement text. Because backslashes are interpreted by both the shell's quoting and by ed, they must be doubled-up twice, which is how one turned into four \\.


• 
  w - write the file back to disk


• 
  q - quit ed