prepending text conditionally

[Dal78]

I am currently writing a script to compare a file list created over an FTP connection to a local directory.
I have cleaned the FTP file list up so that I just have a raw list of filenames however due to the directory structure employed (both locally and on the ftp site) I need to prepend each line with a directory name based on the first letter of the filename. For filenames that are numeric, the directory name is '123'. From this, I can perform a diff in order to give me a manifest of files missing locally to be downloaded using curl or wget.

Suggestions please?

[meton_magis]

awk could be used for this. something along the lines of

awk '$1 ~ /^[1-9].*/ {print "/directory/" $1}'

replacing $1 with whatever column the text is in. Awk breaks stuff down into 2 parts, a condition, and an action. The condition here is 'if column 1 starts with [1-9],' the action is {print /directory/column1}

it's kinda confusing at first, but mess around with it. You could create some complex stuff with it.

[Dal78]

OK I think I get the idea - will have a play

[meton_magis]

you can run it from the command line as shown, but you can also run it as a script file. make a file like

#!/bin/awk
$1 ~ /^[1-9].*/ {print "/directory/" $1}

then run (for example)
echo "123asdf" | awk --exec=filename

it will output

/directory/123asdf

you can add more lines, and it will check each line of input text against all paterns. You can get a lot more advanced, but that is the limit of my awk knowledge.

[Dal78]

Thanks - started playing with awk, but then somebody gave me this suggestion using sed

sed 's|.|/&/&|;s|^/[0-9]|/123|' infile

where infile is the file containing the list of files.