Sponsored Content
Full Discussion: reversing a list
Top Forums Shell Programming and Scripting reversing a list Post 29829 by TioTony on Friday 11th of October 2002 05:42:38 PM
Old 10-11-2002
reversing a list

Hi Everyone,
I am reading in a list of IDs from a file that is is chronological order. My current code in simplified form looks like this (ksh by the way)

IDS=`awk -F\| '{print $1}' inputfile.txt`
for i in $IDS
do
do various things with that ID
done

inputfile.txt looks like this:

1|stuff|more stuff|etc
2|stuff|more stuff|etc
3|stuff|more stuff|etc
.
.
.
10000|stuff|more stuff|etc

What I would like to do is start with the last ID (10000) and work towards the first ID (1). This is an oversimplified example. There are gaps between IDs, the may not be consecutive. I cannot do a while loop starting with i=10000 and decrement to 1 due to this. Any ideas how I could reverse the values in $IDS before the for loop? The input file can be manipulated prior to calling the script. I thought there was a command to invert a list but I can't remember what it is and can't find it ( I searched the forum + google + man -k)
Thanks,
Tony
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Reversing UID's

Is it possible given a uid to determine information about the person with the uid? An example would be simple information regarding what group and the name of the person associated with that uid. It seems there is probably an easy staring me in the face but i cant seem to find it... (3 Replies)
Discussion started by: dreaming1
3 Replies

2. Shell Programming and Scripting

output string in reversing order

If I have string { I_love_shell_scripts} anyone knows how to have output {stpircs_llehs_evol_I} by using shell and perl ?I know in perl, there is reverse() funcation, but can it be done by not using reverse()? (3 Replies)
Discussion started by: ccp
3 Replies

3. Shell Programming and Scripting

awk and reversing

Hello I'm writing script in awk that reverse order the fields of every line in file. My script have problem with spaces - if there is more spaces between fields in line of file - my script erase them . I want my script work like command "tac" - how to change it ? #!/bin/sh file=$1... (1 Reply)
Discussion started by: scotty_123
1 Replies

4. Shell Programming and Scripting

Reversing file order using SED

Im trying to develop a shell script that will change the content order of the file. For example I have a file that says a b c d I want to change this to be d c b a Im trying to use sed to this by reading the file and then inserting each line at the top #!/usr/bin/ksh ... (3 Replies)
Discussion started by: MBGPS
3 Replies

5. Shell Programming and Scripting

reading and reversing a string

Hi Everyone....I am new to Unix and BASH programming...I just want to read a string and reverse it and display.....can anyone help me out???? (8 Replies)
Discussion started by: nikhilneela
8 Replies

6. Shell Programming and Scripting

reversing a line

Hi, I could not find this anywhere and I am wondering if someone knows a quick way of doing this. So heres the problem... I have a row that looks like this (an example): 5 4 3 2 1 What I want to do is reverse it so it looks like this: 1 2 3 4 5 Does anyone know the simple unix... (7 Replies)
Discussion started by: kylle345
7 Replies

7. Shell Programming and Scripting

Need help reversing this code

ssh servername.com "echo /$APP=$BUSIN >> $URI; echo /$APP/*=$BUSIN >> $URI" Ok for example here i ssh into a example servername.com, and I think what it does some line gets put into the urifile , my question is, how would i go about removing that in a script. in summary, the above code is... (3 Replies)
Discussion started by: new2learn09
3 Replies

8. Shell Programming and Scripting

reversing order of lines in a file

how can i reverse the line order in text files? (but total number of the lines is not constant ) for example i have a file like this: line1 line2 line3 . . lineN i wantto make it like this: lineN . . . line3 (26 Replies)
Discussion started by: gfhgfnhhn
26 Replies

9. Shell Programming and Scripting

reversing multiple lines

Hi I want to reverse multiple lines from my file eg of File1 3 4 5 6 7 8 9 a b c d e f g h I am using this code to reverse lines but it can only work with one row awk -F'\t' '{while (NF){printf("%s%s", $(NF--),!NF?"":FS)}}' File1 > File2 I want the file to look like this 9 8 7 6 5 4... (2 Replies)
Discussion started by: phil_heath
2 Replies

10. Shell Programming and Scripting

Reversing a line based on column

Hi, I have a file that looks like this (tab seperated): read - DFHJ read1 - IOPE read2 + AAAB read3 + MMMN Basically what i want to do is reverse column 3 if column 2 has a - but leave it if its + so the output would look like this: read - JHFD read1 - EPOI read2 + AAAB... (3 Replies)
Discussion started by: kylle345
3 Replies
MooseX::AttributeHelpers::MethodProvider::List(3pm)	User Contributed Perl Documentation    MooseX::AttributeHelpers::MethodProvider::List(3pm)

NAME
MooseX::AttributeHelpers::MethodProvider::List - method generator for MooseX::AttributeHelpers::Collection::List SYNOPSIS
package Stuff; use Moose; use MooseX::AttributeHelpers; has 'options' => ( metaclass => 'Collection::List', is => 'rw', isa => 'ArrayRef[Str]', default => sub { [] }, auto_deref => 1, provides => { elements => 'all_options', map => 'map_options', grep => 'filter_options', find => 'find_option', first => 'first_option', last => 'last_option', get => 'get_option', join => 'join_options', count => 'count_options', empty => 'do_i_have_options', sort => 'sorted_options', } ); no Moose; 1; DESCRIPTION
This is a role which provides the method generators for MooseX::AttributeHelpers::Collection::List. METHODS
meta PROVIDED METHODS
count Returns the number of elements in the list. $stuff = Stuff->new; $stuff->options(["foo", "bar", "baz", "boo"]); my $count = $stuff->count_options; print "$count "; # prints 4 empty If the list is populated, returns true. Otherwise, returns false. $stuff->do_i_have_options ? print "Good boy. " : die "No options! " ; find This method accepts a subroutine reference as its argument. That sub will receive each element of the list in turn. If it returns true for an element, that element will be returned by the "find" method. my $found = $stuff->find_option( sub { $_[0] =~ /^b/ } ); print "$found "; # prints "bar" grep This method accepts a subroutine reference as its argument. This method returns every element for which that subroutine reference returns a true value. my @found = $stuff->filter_options( sub { $_[0] =~ /^b/ } ); print "@found "; # prints "bar baz boo" map This method accepts a subroutine reference as its argument. The subroutine will be executed for each element of the list. It is expected to return a modified version of that element. The return value of the method is a list of the modified options. my @mod_options = $stuff->map_options( sub { $_[0] . "-tag" } ); print "@mod_options "; # prints "foo-tag bar-tag baz-tag boo-tag" sort Sorts and returns the elements of the list. You can provide an optional subroutine reference to sort with (as you can with the core "sort" function). However, instead of using $a and $b, you will need to use $_[0] and $_[1] instead. # ascending ASCIIbetical my @sorted = $stuff->sort_options(); # Descending alphabetical order my @sorted_options = $stuff->sort_options( sub { lc $_[1] cmp lc $_[0] } ); print "@sorted_options "; # prints "foo boo baz bar" elements Returns all of the elements of the list my @option = $stuff->all_options; print "@options "; # prints "foo bar baz boo" join Joins every element of the list using the separator given as argument. my $joined = $stuff->join_options( ':' ); print "$joined "; # prints "foo:bar:baz:boo" get Returns an element of the list by its index. my $option = $stuff->get_option(1); print "$option "; # prints "bar" first Returns the first element of the list. my $first = $stuff->first_option; print "$first "; # prints "foo" last Returns the last element of the list. my $last = $stuff->last_option; print "$last "; # prints "boo" BUGS
All complex software has bugs lurking in it, and this module is no exception. If you find a bug please either email me, or add the bug to cpan-RT. AUTHOR
Stevan Little <stevan@iinteractive.com> COPYRIGHT AND LICENSE
Copyright 2007-2009 by Infinity Interactive, Inc. <http://www.iinteractive.com> This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.10.1 2010-01-02 MooseX::AttributeHelpers::MethodProvider::List(3pm)
All times are GMT -4. The time now is 02:12 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy