delete last line from text file Post: 23558

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Top Forums Shell Programming and Scripting delete last line from text file Post 23558 by Perderabo on Tuesday 25th of June 2002 09:52:51 AM

06-25-2002

Administrator Emeritus

$ means the last line. But sed doesn't know that it has the last line until it arrives. You can't do a "sed '$-1d'" or anything. Deleting the next to the last line via sed is very hard. So hard that I would normally use other techniques. But just for the heck of it, I finally got a sed script running that deletes the next to the last line:

Code:

#! /usr/bin/sed -nf
#
${P
q
}
1{h
d
}
x
p

And this solution will not easily scale up. A sed script to delete $-2 will take about 10 times the code. Deleting $-3 would be a nightmare. The problem is that you don't know in advance how many lines there are. To really have a general solution, you need to make two passes through the file. On the first pass, you count the lines. On the second pass, you delete the appropriate line. sed cannot do this alone since it always will only make a single pass through the file.

Code:

#! /usr/bin/ksh
lines=$(wc -l $1)
((target=lines-1))
sed "${target}d" < $1
exit 0

Now we have an extensible solution.

Perderabo

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LEARN ABOUT V7

asadmin-delete-domain

asadmin-delete-domain(1AS)					   User Commands					asadmin-delete-domain(1AS)

NAME

       asadmin-delete-domain, delete-domain - deletes the givendomain

SYNOPSIS

       delete-domain [--terse=false] [--echo=false] [--domaindir install_dir/domains] domain_name

       delete-domain  deletes  the  specified  domain.	The domain must already exist and must be stopped. This command is supported in local mode
       only.

OPTIONS

       --domaindir	       directory where the domain is to be deleted. If specified, path must be accessible in the filesystem. If not speci-
			       fied, the domain in the default install_dir/domains directory is deleted.

       --terse		       indicates that any output data must be very concise, typically avoiding human-friendly sentences and favoring well-
			       formatted data for consumption by a script. Default is false.

       --echo		       setting to true will echo the command line statement on the standard output. Default is false.

OPERANDS

       domain_name	       name of the domain. Must be a unique name.

       Example 1: Using delete-domain

       asadmin> delete-domain sampleDomain
       deleted domain sampleDomain successfully

       Where: the sampleDomain domain is deleted.

EXIT STATUS

       0		       command executed successfully

       1		       error in executing the command

       asadmin-create-domain(1AS), asadmin-start-domain(1AS), asadmin-stop-domain(1AS), asadmin-list-domains(1AS)

J2EE 1.4 SDK							    March 2004						asadmin-delete-domain(1AS)

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