Updating file in loop

braindrain · #1 (**permalink**) 06-19-2007

Hi,
I have a file list containing list of characters to be searched and replaced 'file_master'. I have a datafile 'file_data'.
Now, in a loop how do I ensure I'm updating the latest updated file_data when I read the next line of file_master ?

file_master
a , 1
b , 2

file_ data
hello abc
baby
barbe
.....

Quote:

while read dat_file;do
for lkp_file in `cat file_master`
do
echo $dat_file | sed -e "s,fieldtobereplaced,fieldreplacedvalue,g"
done < $2
done < $1

where $1 is file_data and and $2 is file_master.

i.e I expect output to be

file_ data :

hello 12c
212y
21r2e

Does the above, make sure for each and every line of master, data is updated ? . It doesn't seem to work

Shell_Life · #2 (**permalink**) 06-19-2007

Code:

while read mLine
do
  set -- `echo $mLine | sed 's/,/ /'`
  sed "s/$1/$2/" file_data > $$Temp_File
  mv $$Temp_File file_data
done < file_master
rm -f $$Temp_File

aigles · #3 (**permalink**) 06-19-2007

Another way is to use the tr command.

Code:

while read line_master
do
   set -- `echo $line_master | sed 's/,/ /'`
   from="$from$1"
   to="$to$2"
done < file_master
tr "$from" "$to" < file_data >file_data.$$
mv file_data.$$ file_data

The problem with this solution is that special characters, like space, comma, double quote, backslash arent't supported (same thing for Shell_life solution)

braindrain · #4 (**permalink**) 06-20-2007

aigles/shell_life, thanks for the reponse.

fyi, I'm trying to replace all the special characters like
Ø Ù Ú Û Ü Ý Þ ß etc.,

For those charcter you mentioned(spaces, backslash, single quote, comma),Cant we use a escape sequence? For instance I can used sed to change comma, if I use different delimiter other than comma.

braindrain · #5 (**permalink**) 06-20-2007

To be precise,
my file_master can have following character, field1 need to be converted to field2 ( \,+\-,\\ etc)

Quote:

§ \
± +\-
¶ \\
¼ 1\4
½ 1\2
¾ 3\4
÷ \

Ofcourse I can do with multiple sed's
like below

sed -e 's,÷,\\,g' $src > $src$$
[[ $? -ne 0 ]] && [[ -s $src ]] && mv $src$$ $src || exit 3
sed -e 's,±,\\,g' $src > $src$$
[[ $? -ne 0 ]] && [[ -s $src ]] && mv $src$$ $src || exit 4

but wandering if it can be achevied in master and data file approach (without hardcoding in sed command) .

I tried, giving input as ,÷,\\ and ,±,\\ , however when it reads it strips one of the backslash and sed fails.

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