Sorting strings in reverse order Post: 302724107

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Top Forums Shell Programming and Scripting Sorting strings in reverse order Post 302724107 by drl on Wednesday 31st of October 2012 08:14:41 AM

10-31-2012

Registered User

Hi.

Among the many additional features of utility msort compared to standard sort is the ability to specify a reverse sequence of keys:

Code:

#!/usr/bin/env bash

# @(#) s1	Demonstrate reversed character key sequencing, msort.
# See: http://freecode.com/projects/msort

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C msort

FILE=${1-data1}

pl " Input data file $FILE:"
cat $FILE

pl " Results, normal key sequencing:"
msort -q --line -n 1,1 $FILE

pl " Results, reversed key sequencing:"
msort -q --line -n 1,1 -R $FILE

exit 0

producing:

Code:

% ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0.8 (lenny) 
bash GNU bash 3.2.39
msort 8.44

-----
 Input data file data1:
John
Mary
Henry
does
doing
writes

-----
 Results, normal key sequencing:
Henry
John
Mary
does
doing
writes

-----
 Results, reversed key sequencing:
doing
John
does
writes
Mary
Henry

The msort code was in the Debian repository (as well as Fedora, Ubuntu, and FreeBSD). See site mentioned in script for others.

Best wishes ... cheers, drl

drl

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LEARN ABOUT OPENDARWIN

printenv

PRINTENV(1)						    BSD General Commands Manual 					       PRINTENV(1)

NAME

     printenv, env -- print out the environment, set and print environment

SYNOPSIS

     printenv [name]
     env [-i] [name=value ...] [utility [argument ...]]

DESCRIPTION

     The printenv utility prints out the names and values of the variables in the environment, with one name/value pair per line.  If name is
     specified, only its value is printed.

     Some shells may provide a builtin printenv command which is similar or identical to this utility.	Consult the builtin(1) manual page.

     The env utility executes utility after modifying the environment as specified on the command line.  The option name=value specifies an envi-
     ronment variable, name, with a value of value.

     The options are as follows:

     -i      Execute the utility with only those environment values specified.	The environment inherited by env is ignored completely.

     If no utility is specified, env prints out the names and values of the variables in the environment, with one name/value pair per line.

     The env utility is sometimes useful with the ``#!'' construct (see execve(2)).  The only difference between ``#!/usr/local/bin/foo'' and
     ``#!/usr/bin/env /usr/local/bin/foo'' is that the latter works even if /usr/local/bin/foo is itself interpreted.  Using env this way also
     allows one to reference foo without the path, as well as set up the environment as desired.

ENVIRONMENT

     The env utility uses the PATH environment variable is used to locate the requested utility if the name contains no '/' characters.

DIAGNOSTICS

     The printenv utility exits 0 on success, and >0 if an error occurs.

     The env utility exits 0 on success, and >0 if an error occurs.  An exit status of 126 indicates utility was found, but could not be executed.
     An exit status of 127 indicates utility could not be found.

COMPATIBILITY

     The env utility accepts the - option as a synonym for -i.

SEE ALSO

     csh(1), sh(1), execvp(3), environ(7)

STANDARDS

     The env utility conforms to IEEE Std 1003.1-2001 (``POSIX.1'').

HISTORY

     The printenv command appeared in 3.0BSD.

BUGS

     The env utility doesn't handle utility arguments with equal (``='') signs in their names, for obvious reasons.

BSD
								   June 6, 1993 							       BSD