Shell Programming and Scripting

The objective of the code below is to create sed script to be later executed. However, it bonks because $ARCHIVENAME expands to a directory specification so the forward slashes cause problems. I can think of a few solutions that would involve redesigning the process, but I'm hoping there might be something I can do inline by way of escaping the slashes that might allow me to keep my basic logic intact.

Code:

cut -f1 -d "|" $ARCHIVENAME/changes.dat | sed "s/^.*/grep & $ARCHIVENAME\/clean_*/g" > $ARCHIVENAME/create_message_names

Thanks in advance,
Al

Code:

cut -f1 -d "|" $ARCHIVENAME/changes.dat | sed "s#^.*#grep & $ARCHIVENAME/clean_*#g" > $ARCHIVENAME/create_message_names

You can use nearly any non-special character as the delimiter, not just forward slash. Try an expression like s#a#b#g instead of s/a/b/g
If you can pick a character you're guaranteed will never show up in your paths, all the better.
[edit] Jinx!

Code:

.... sed "s:^.*:grep & $ARCHIVENAME/clean_*:g"  ....

If your file is a "real" *.dat file, it may not be a good idea to process it as if it were an pure ASCII text file (i guess the first 1041 bits should be skipped or something like this.
Maybe you should use the "strings" command at first.

By the way using the global substition in that case seems to me quite erroneous since ^.* will match the entire line, only 1 substitution will occure so you should remove the g.

If your final goal is to grep a list of pattern to $ARCHIVENAME/clean_*, you may want to try to use fgrep or grep -f or egrep -f instead of building a file with multiple
grep <pattern> $ARCHIVENAME/clean_* in it.

As has been mentioned, you could use a different regular expression delimiter, a character that you know will never appear in the pathname.

Instead of

Code:

sed "s/^.*/grep &/g"

you can use

Code:

sed "s@^.*@grep &@g"

if the at symbol will never be used.

That said, interpolating values like that is fragile when the tool does not support some form of quoting to strip special meaning from metacharacters (at least in this case it's in the replacement text, otherwise you'd have more special characters to worry about if the parameter expansion were ocurring in the regular expression section of the sed command. Even so, ampersand is still special in this context, though admittedly not very likely to appear in a pathname.).

To be safe, to simplify, and to minimize stress, I would tend to prefer something that avoids interpolating into special contexts as much as possible. Possible alternatives:

Code:

awk -F\| -v aname="$ARCHIVENAME" {print "grep " $1 " \"" aname "\"/clean_*" > (aname"/create_message_names")}'

or

Code:

while IFS=\| read -r pattern junk; do
    printf 'grep %s "%s"/clean_*\n' "$pattern" "$ARCHIVENAME" > "$ARCHIVENAME"/create_message_name
done

Regards,
Alister