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Shell Script Question Read Parameters from a textfile

  • 17-01-2011 10:25AM
    #1
    supermonkey
    Closed Accounts Posts: 144 ✭✭


    Hi all,

    The script below is intended to help in exporting a wordpress website from a staging server to a domain.

    It accepts 2 inputs an old domain and a new domain. These are put in manually at the start of the export process.

    I would like to read in a list of old domains and new domains in the following format
    fish.staging.ie:ilovefish.ie
cows.staging.ie:thecowssite.com
love.staging.ie:whatislove.net

    and have the process run automatically.

    This is the process as it stands I prompt myself for both values. 
    #!/bin/bash
#Script to alter text in database in order to prepare a 
#wordpress website for export
read -p "Enter the old  domain name :   " OLD_DOMAIN
read -p "Enter the new domain name :   " NEW_DOMAIN

PATH_TO="/supermonkey/newsites/"

/usr/bin/mysqldump  -f -u "DBUSER""$OLD_DOMAIN" -p[PASSWORD] "$OLD_DOMAIN" 
>""$PATH_TO"/"$NEW_DOMAIN"/"$NEW_DOMAIN".SQL"
SQL_FILE=""$PATH_TO"/"$NEW_DOMAIN"/"$NEW_DOMAIN".SQL"


sed "s|$OLD_DOMAIN|$NEW_DOMAIN|g" "$PATH_TO"/"$OLD_DOMAIN"/"$OLD_DOMAIN".SQL> "$PATH_TO"/"$OLD_DOMAIN"/"$NEW_DOMAIN""01"".SQL"

    I tried this before and it worked but only if the file only contained 1 pair of values. Otherwise the sed happened at what looked like random. 
    #!/bin/bash

#Script to read a list of files and convert databases
while IFS=: read OLD_DOMAIN NEW_DOMAIN
do  


done < /home/supermonkey/allsites/supmdomainlist.txt


Comments

  • #2
    Skrynesaver
    Registered Users, Registered Users 2 Posts: 1,110 ✭✭✭Skrynesaver 


    ~/src $ cat test.txt
one:two
three:four
~/src $ for i in $(cat test.txt);do first=$(echo $i|cut -d\: -f1);second=$(echo $i |cut -d\: -f2 );echo "First is $first and Second is $second";done;
First is one and Second is two
First is three and Second is four


  • #3
    supermonkey
    Closed Accounts Posts: 144 ✭✭supermonkey


    Thanks Skrynesaver,
    The example works.
    Now I have to understand it and relate it to my own script. 
    for i in $(cat test.txt);
do first=$(echo $i|cut -d\: -f1);
second=$(echo $i |cut -d\: -f2 );
echo "First is $first and Second is $second";
done;

    for i in $(cat test.txt);
    Sets up a for loop.
    How does UNIX know that the counter and the line number are the same?
    Is any file that we cat assumed to contain meaningful records? 
    do first=$(echo $i|cut -d\: -f1);
second=$(echo $i |cut -d\: -f2 );
    echo $i gets the counter and therefore the line number
    cut -d\: specifies that the field delimiter is :
    first is assigned to field 1 -f1
    second is assigned to field 2 -f2


  • #4
    Skrynesaver
    Registered Users, Registered Users 2 Posts: 1,110 ✭✭✭Skrynesaver


    supermonkey wrote: »
    Thanks Skrynesaver,
    The example works.
    Now I have to understand it and relate it to my own script.

    :D

    The notion is to treat each line as a record $i then use cut to isolate specific fields using a field separator ":"
    The cut command takes a delimiter and a field to return.
    This was a quick hack, hope it can be integrated :)


  • #5
    supermonkey
    Closed Accounts Posts: 144 ✭✭supermonkey


    Skrynesaver wrote: »
    The notion is to treat each line as a record $i then use cut to isolate specific fields using a field separator ":"
    The cut command takes a delimiter and a field to return.
    This was a quick hack, hope it can be integrated :)
    Is each line being a record implicit in when you cat a file? I really have to get a handle on piping!!!:p


  • #6
    Skrynesaver
    Registered Users, Registered Users 2 Posts: 1,110 ✭✭✭Skrynesaver


    supermonkey wrote: »
    Is each line being a record implicit in when you cat a file? I really have to get a handle on piping!!!:p

    There is a shell variable $IFS which is used by the for loop to determine where each record ends.

    It's not a c style for loop, it assigns the value of the current record to $i in the loop,


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  • #7
    supermonkey
    Closed Accounts Posts: 144 ✭✭supermonkey


    Skrynesaver wrote: »
    There is a shell variable $IFS which is used by the for loop to determine where each record ends.
    And that variable is newline by default? Meaning that if I use newline I don't specify $IFS? I really got this wrong. Thought $IFS was the field delimiter no wonder it didn't work!


  • #8
    Skrynesaver
    Registered Users, Registered Users 2 Posts: 1,110 ✭✭✭Skrynesaver


    supermonkey wrote: »
    And that variable is newline by default? Meaning that if I use newline I don't specify $IFS? I really got this wrong. Thought $IFS was the field delimiter no wonder it didn't work!

    IFS (Internal Field Seperator) is the field delimiter, but we're treating the field the for loop isolates as a record.


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