Shell Programming and Scripting

This should get rid of spaces around the backslash:

Code:

sed ':a;N;s/[ \t]*\\\n[ \t]*/ /;ba' infile

It creates a label a ( a: )
It then joins two lines ( N )
After that leadings space before and after a \ followed by a linefeed (\n) get replaced by a single space
Then it branches (b) to label a.

This works great. Thanks :-)

OK, you've given me pretty much exactly what I asked for but this has only highlighted the fact that I mis-stated exactly what I wanted. Ultimately, I'm trying to generate a list of hosts that are represented in the sudoers file. This sed statement (which actually only works if I use gsed on my Solaris 10 host) now leaves me with something like this:

Host_Alias ALIAS1=host1,host2,host3

Host_Alias ALIAS2=host1,host3,host4,host5
Host_Alias ALIAS3=host1,host5,host6

etc.

OK, I can removed blank lines with grep or awk and I can chop off everything up to the = character with another sed statement and I might use tr, for example, to replace all the , characters with a newline character and I'm sure this would all get me what I want.

But ... could it ALL be done in a single command? List every host that's represented in the sudoers file?

- CDM

---------- Post updated at 11:22 AM ---------- Previous update was at 11:11 AM ----------

This is the shortest pipeline I can come up with:

# gsed ':a;N;s/[ \t]*\\\n[ \t]*//;ba;s/*=//g' /etc/sudoers | \
awk -F= '/^Host_Alias/ {print $NF}' | \
tr ',' '\n' | \
sort | \
uniq

Alternatively:

Code:

sed ':a;N;s/[ \t]*\\\n[ \t]*//;ba' /etc/sudoers|sed -n 's/^Host_Alias.*=//;s/,/\n/gp'|sort -u

This doesn't filter out all the non Host_Alias entries in the file (sorry, that's me not stating the problem correctly again).

What's the significance of the -n and the p after the g?

- CDM

How about this?

Code:

sed ':a;N;s/[ \t]*\\\n[ \t]*//;ba' /etc/sudoers|sed -n '/^Host_Alias/{s/.*=//;s/,/\n/gp}'|sort -u

-n means do not print pattern space automatically
p means print the pattern space

Hmmm. OK, this works fine (but, again, only if I use gsed) but it does not capture entries that have only a single host listed like this:

Host_ALias ALIAA8=host12

I suspect because of the assumption of a comma being present on the line?

- CDM

I can do this:

Code:

sed ':a;N;s/[ \t]*\\\n[ \t]*//;ba' /etc/sudoers |
sed '/^Host_Alias/!d;{s/.*=//;s/,/\n/g;s/$/\n/p}'|sort -u

But that does not make it any easier and it prints a blank line

Or this:

Code:

awk -F '[, \t \\\]*' '/Host_Alias/,!/\\/{sub(/^Host_Alias.*=/,"");print}' /etc/sudoers |
grep -o '\w\+' |sort -u

But I don't see how this is an improvement really on what you created yourself (yawn).