遍历文件并使用sed将旧值替换为新值

Question

Im trying to write a script in which a while loop reads a file line by line, performs a command on two values on that line (to get two new values), then replaces the two old values with the two new values, then moves on to the next line.

For example the txt file example.txt contains the following data:

 1432771200 != 1432800000 OPTION VALUE
 1432771200 != 1432800210 OPTION VALUE
 1432771200 != 1432800033 OPTION VALUE

And I run the following script:

 #!/bin/bash -x
 #
    while read line
    do
            arr=($line)
            CURRENTDATE=`h2e ${arr[0]}`
            PROPOSEDDATE=`h2e ${arr[2]}`
            echo $CURRENTDATE
            echo $PROPOSEDDATE
    #       echo $line |
            sed -i "s/${arr[0]}/$CURRENTDATE/"
    #       echo $line |
            sed -i "s/${arr[2]}/$PROPOSEDDATE/"
    done < /srg/pro/data/example.txt

What I expect to see now in example.txt file is the replacement of the first and third value on each line.. so it should look like this:

 Thu May 28 01:00:00.000 2015 BST != Thu May 28 09:00:00.000 2015 BST OPTION VALUE
 Thu May 28 01:00:00.000 2015 BST != Wed May 27 01:00:00.000 2015 BST OPTION VALUE
 Fri May 28 01:00:00.000 2015 BST != Fri May 29 06:00:00.000 2015 BST OPTION VALUE

And so on and so forth..

When I run the shell script with bash -x Interface.sh Im getting this:

 read line
 + arr=($line)
 ++ h2e 1432771200
 + CURRENTDATE='1432771200.000  2015148  Thu May 28 01:00:00.000 2015 BST (1)'
 ++ h2e 1432800000
 + PROPOSEDDATE='1432800000.000  2015148  Thu May 28 09:00:00.000 2015 BST (1)'
  + echo 1432771200.000 2015148 Thu May 28 01:00:00.000 2015 BST '(1)'
   1432771200.000 2015148 Thu May 28 01:00:00.000 2015 BST (1)
   + echo 1432800000.000 2015148 Thu May 28 09:00:00.000 2015 BST '(1)'
   1432800000.000 2015148 Thu May 28 09:00:00.000 2015 BST (1)
 + sed -i 's/1432771200/1432771200.000  2015148  Thu May 28 01:00:00.000       2015 BST (1)/'
 sed: no input files
 + sed -i 's/1432800000/1432800000.000  2015148  Thu May 28 09:00:00.000   2015 BST (1)/'
 sed: no input files
 + read line
 + arr=($line)
 ++ h2e 1432771200
 + CURRENTDATE='1432771200.000  2015148  Thu May 28 01:00:00.000 2015 BST (1)'
 ++ h2e 1432800000
+ PROPOSEDDATE='1432800000.000  2015148  Thu May 28 09:00:00.000 2015 BST  (1)'
 + echo 1432771200.000 2015148 Thu May 28 01:00:00.000 2015 BST '(1)'
 1432771200.000 2015148 Thu May 28 01:00:00.000 2015 BST (1)
 + echo 1432800000.000 2015148 Thu May 28 09:00:00.000 2015 BST '(1)'
 1432800000.000 2015148 Thu May 28 09:00:00.000 2015 BST (1)
 + sed -i 's/1432771200/1432771200.000  2015148  Thu May 28 01:00:00.000 2015 BST (1)/'
 sed: no input files
+ sed -i 's/1432800000/1432800000.000  2015148  Thu May 28 09:00:00.000 2015 BST (1)/'
sed: no input files 

Please help! Dont know how to fix this!

Answer 1

Using your batch (there are other way)

#!/bin/bash -x
 #
  cp /srg/pro/data/example.txt /tmp/temp.file

  cat /srg/pro/data/example.txt \
  | while read line
    do
            arr=($line)
            CURRENTDATE=`h2e ${arr[0]}`
            PROPOSEDDATE=`h2e ${arr[2]}`
            echo $CURRENTDATE
            echo $PROPOSEDDATE
    #       echo $line |
            sed -i "s/${arr[0]}\(.*\)${arr[2]}/${CURRENTDATE}\1${PROPOSEDDATE}/" /tmp/temp.file
    done

mv /tmp/temp.file /srg/pro/data/example.txt 

• sed -i does not work on stream, need a file
• I use a temporary file to avoid problem reading the same file that is modified inside the loop that often create unexpected result (like empty file)
• this work for your sample but it depend of line structure for your array and sed substitution in real structure of data file

Answer 2

The read command can read split the line into fields:

outfile=/tmp/some_tmp_file_you_will_move
while read date1 marker date2 otherfields; do
    CURRENTDATE=`h2e ${date1}`
    PROPOSEDDATE=`h2e ${date2}`
    echo $CURRENTDATE
    echo $PROPOSEDDATE
    echo "${CURRENTDATE} ${marker} ${PROPOSEDDATE} ${otherfields}" >> ${outfile}
done < /srg/pro/data/example.txt

When you don't need to see the CURRENTDATE/PROPOSEDDATE inside your loop, you can redirect the output outside the loop for a better performance:

outfile=/tmp/some_tmp_file_you_will_move
while read date1 marker date2 otherfields; do
    CURRENTDATE=`h2e ${date1}`
    PROPOSEDDATE=`h2e ${date2}`
    echo "${CURRENTDATE} ${marker} ${PROPOSEDDATE} ${otherfields}"
done < /srg/pro/data/example.txt > ${outfile}

Note: Consider using $(h2e ...) and not ``