UNIX for Advanced & Expert Users

I thought this would be easy to Google, but I am having trouble getting a clean result that I can understand.

I simply want to insert the the line:
My Network 192.168.1.1

After the last line that begins with ACL localnet

Try:

Code:

#!/bin/ksh
ed - in.addafter <<EOF
?^ACL localnet?a
My Network 192.168.1.1 
.       
w       
EOF

Is ed - intended to be ed -s?

I'm not sure if "After the last line that begins with ACL localnet" means that there is only one match and that it occurs on the last line of the file, or if it means that there may be multiple matches. If the latter, I would suggest moving to line 1 before beginning the backwards search. As it is, if the final match is the last line, and if there is an earlier match, the earlier match will "win".

Regards,
Alister

Don't use it.

Code:

lem@biggy:/tmp$ line=$(sed -n '/^ACL localnet/ =' file |tail -n1)
lem@biggy:/tmp$ (( ${line:-0} == 0 )) || { rm file ; sed  "$line a\
My Network 192.168.1.1" > file ; } <file

I said don't use it.
--
Bye

Yes. Thank you for catching this. I thought I typed the "s", but it isn't in my test script.

The POSIX standard says that a "-" operand produces unspecified results. On some systems, "-" is a synonym for "-s"; on other systems "-" is a file operand referring to ed's standard input. On OS X (the OS on my primary machine), "-" and "-s" are synonyms so I didn't notice the typo when I was testing.

You are also correct in noting that the current line is set to the last line in the buffer when a file is loaded into the buffer by the e command, the E command, or by naming a file operand on the command line.

Note that the following script could just use the command 1 (digit one; not letter el), but that would print the first line. Substituting the start of line 1 to nothing doesn't change anything on the line, but changes the current line to the 1st line in the buffer without printing anything.

Code:

#!/bin/ksh
ed - in.addafter <<EOF
1s/^//
?^ACL localnet?a
My Network 192.168.1.1
.
w
q
EOF

Note that although I specified /bin/ksh for this script, any shell should work. I tested it with ksh, bash, csh, sh, and tcsh.

I mean that there are multiple lines that begin with ACL localnet and I want to insert a line after the last instance.

An alternate approach:

Code:

awk -v cache=/tmp/PID$$.cache '
    function print_cache(       rec )
    {
        if( ! buffer )
            return;

        close( cache );
        while( (getline rec <cache ) > 0 )
            print rec;
        close( cache );
    }

    /^ACL localnet/ {
        print_cache();
        print;
        buffer = 1;
        next;
    }

    {
        if( buffer )
            print >cache;
        else
            print;
        next;
    }

    END {
        if( buffer )
            print "My Network 192.168.1.1 "
        print_cache( );
        system( "rm " cache );
    }
'  input-file >output-file

Doesn't insert the line if the pattern isn't found.