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Top Forums Shell Programming and Scripting Linux shell programming performance issue Post 302915099 by RudiC on Sunday 31st of August 2014 04:00:15 PM
Old 08-31-2014
You don't need awk (or similar) to improve the performance of your script. Just by the look on it, it can be seen that you run six commands (= six new processes) in the inner loop, times 50 for the lines in file 2, times millions for the lines in file1 (opening file2 millions times (even though buffered/cached)).

With your input data, and after cleaning out a few quirks in your code snippet, I find
Code:
time . XX
real    0m0.308s
user    0m0.192s
sys    0m0.119s

, while
Code:
time . YY
real    0m0.014s
user    0m0.012s
sys    0m0.000s

with YY being
Code:
while IFS='' read -r line
         do     while IFS=, read field1 field2
                        do      TMP=${line//$field1}
                                if [ $(( (${#line}- ${#TMP}) / ${#field1} )) -gt 1 ]
                                        then    sed  "s/"$field1"/"$field2"/2g"  <<<"$line" >> tmp.txt
                                        break
                                fi
                        done < file2
        done < file1
cat tmp.txt
TEXAS CALIFORNIA TX
DALLAS CALIFORNIA CALIFORNIA DA DA TEXAS

An even faster solution might be to use an array to hold file2's contents, and have the outer loop read file1, and an inner loop to iterate through the array doing the comparisons/modifications.

---------- Post updated at 22:00 ---------- Previous update was at 21:36 ----------

Modification using arrays; adapt to taste...:
Code:
unset i
while IFS=, read field1[++i] field2[i]; do : ; done < file2
while IFS='' read -r line
         do     for (( i=1; i<=${#field1[@]}; i++ ))
                        do      TMP=${line//${field1[$i]}}
                                if [ $(( (${#line}- ${#TMP}) / ${#field1[$i]} )) -gt 1 ]
                                        then    sed "s/"${field1[$i]}"/"${field2[$i]}"/2g"  <<<"$line" >> tmp.txt
                                        break
                                fi
                        done
        done < file1

Timing is similar to the first version; looks like the disk cache is quite powerful:
Code:
time . ZZ

real    0m0.015s
user    0m0.003s
sys    0m0.013s

 

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SNIFFIT(5)							File Formats Manual							SNIFFIT(5)

NAME
sniffit - configuration file for sniffit (name arbirtary) DESCRIPTION
This page describes the format for the config file for sniffit (see sniffit(8) ). This file allows you to specify in great detail witch packets should be processed by sniffit. This file also controls (or will control) some functions for the continuous logging ('-L' option). A sniffit config file might look like (Be sure to end it with a BLANK line): # Sniffit Sample Config file -- Brecht Claerhout logfile /var/log/sniffit.today.log # First select all packets! select both mhosts 1 select both mhosts 2 # Now deselect all packets from/to those damn 'surfers' deselect both port 80 deselect both port 8001 This file will tell sniffit to process all packets on the subnet except those FROM/TO ports 80 and 8001 (thus we don't want logs of those mass WWW connections witch turn our logs unreadable). GLOBAL FORMAT
The file consists of lines, lines are formed by fields, fields are separated with SPACES (NO TABS). Unix comment lines (starting with '#' are allowed). So this gives us: <field1> <field2> <field3> <field4> <field5> FIELD FORMAT
<field1> select - Sniffit will look for packets that match the following description (other fields) deselect - Sniffit will ignore packets that match the description logfile - change the logfile name to <field2> instead of the default 'sniffit.log' <field2> from - Packets FROM the host matching the following desc. are considered. to - similar, Packets TO the.... both - similar, Packets FROM or TO the.... a filename - as an argument of 'logfile' in <field1> <field3> host - The (de)selection criteria involves a hostname. port - similar, ... a portnumber mhosts - The (de)selection criteria involves multiple-hosts, like with the wildcars in 0.3.0, but without the 'x' <field4> Either a hostname, a portnumber, a service name or a numbet-dot partial notation indicating multiple hosts depending on <field3> (service names like 'ftp' are resolved as the services available present on the host that runs Sniffit, and translated into a port nr) <field5> A portnumber, if <field3> was 'host' or 'mhosts' (optional, if not filled in, all ports are going to be (de)selected) FILE INTERPRETING
The config file is interpreted SEQUENTIAL, so watch it, don't mix lines in a file. Example: select both mhosts 100.100.12. deselect both port 80 select both host 100.100.12.2 This file will get you the packets: a) Send by hosts '100.100.12.*' b) EXCEPT the WWW packets c) BUT showing the WWW packets concerning 100.100.12.2 select both mhosts 100.100.12. select both host 100.100.12.2 deselect both port 80 Will give you the packets (probably unwanted result): a) Send by hosts '100.100.12.*' b) Send from/to 100.100.12.2 (useless line) c) deselecting all WWW packets on the subnet AUTHOR
Brecht Claerhout <coder@reptile.rug.ac.be> SEE ALSO
sniffit(8) SNIFFIT(5)
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