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
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LEARN ABOUT LINUX
git-stripspace
GIT-STRIPSPACE(1) Git Manual GIT-STRIPSPACE(1)
NAME
git-stripspace - Remove unnecessary whitespace
SYNOPSIS
git stripspace [-s | --strip-comments] < input
DESCRIPTION
Clean the input in the manner used by Git for text such as commit messages, notes, tags and branch descriptions.
With no arguments, this will:
o remove trailing whitespace from all lines
o collapse multiple consecutive empty lines into one empty line
o remove empty lines from the beginning and end of the input
o add a missing
to the last line if necessary.
In the case where the input consists entirely of whitespace characters, no output will be produced.
NOTE: This is intended for cleaning metadata, prefer the --whitespace=fix mode of git-apply(1) for correcting whitespace of patches or
files in the repository.
OPTIONS
-s, --strip-comments
Skip and remove all lines starting with comment character (default #).
-c, --comment-lines
Prepend comment character and blank to each line. Lines will automatically be terminated with a newline. On empty lines, only the
comment character will be prepended.
EXAMPLES
Given the following noisy input with $ indicating the end of a line:
|A brief introduction $
| $
|$
|A new paragraph$
|# with a commented-out line $
|explaining lots of stuff.$
|$
|# An old paragraph, also commented-out. $
| $
|The end.$
| $
Use git stripspace with no arguments to obtain:
|A brief introduction$
|$
|A new paragraph$
|# with a commented-out line$
|explaining lots of stuff.$
|$
|# An old paragraph, also commented-out.$
|$
|The end.$
Use git stripspace --strip-comments to obtain:
|A brief introduction$
|$
|A new paragraph$
|explaining lots of stuff.$
|$
|The end.$
GIT
Part of the git(1) suite
Git 1.8.5.3 01/14/2014 GIT-STRIPSPACE(1)