bug-bash
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Bad performance for substring replacement by pattern


From: Yi Yan
Subject: Bad performance for substring replacement by pattern
Date: Mon, 12 Jul 2010 20:27:15 +0000

Hi,

     I used the following Bash script to test substring replacement operator.
It is performance get worse very quickly with the increasing of the string
length.

    I test the script with Bash(4.1) on Debian Linux machine.

    See the execution time difference by increasing the $NUM in the script:


========================================
#! /usr/local/bin/bash

declare z="start"
declare NUM=1000

#----------------------------------
# create a long string with ';'
#----------------------------------
for ((i=0; i<$NUM; i++)); do
    z="$z;string$i"
done


#------------------------------
# delete everything except ';'
#------------------------------
date +%s

x="${z//[^;]}"
echo $x

date +%s


                                          
_________________________________________________________________
The New Busy is not the too busy. Combine all your e-mail accounts with Hotmail.
http://www.windowslive.com/campaign/thenewbusy?tile=multiaccount&ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_4

reply via email to

[Prev in Thread] Current Thread [Next in Thread]