Bash - Appending to specific line in file Post: 302793081

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Top Forums Shell Programming and Scripting Bash - Appending to specific line in file Post 302793081 by Don Cragun on Thursday 11th of April 2013 04:13:16 PM

04-11-2013

Registered User

Quote:

Originally Posted by MadeInGermany

Assumed your filename is "file".
With sed:

Code:

factor="3,6"
trial="YES,18,1.635"
sed '/'"$factor"'|/ s/$/|'"$trial"'/' < file > file.new

With the shell built-ins it becomes a bit long,
so a function makes sense:

Code:

append () {
IFS="|"   
while read factor trial
do
  if [ "$factor" = "$1" ] 
  then
    echo "$factor|$trial|$2"
  else
    echo "$factor|$trial"
  fi
done < file > file.new
}

and call it

Code:

append "3,6" "YES,18,1.635"

---------- Post updated at 02:47 PM ---------- Previous update was at 02:38 PM ----------

The sed version has the problem that it does not have a true field separator.
Here is an awk version:

Code:

awk -F"|" '{if ($1==factor) {print $0 FS trial} else {print}}' factor="3,6" trial="YES,18,1.635" < file > file.new

Unfortunately, both of these examples only work if all possible values of factor are in file before you try to add a new trial. If you want to start with an empty file and add new entries (as well as update existing entries), you could try these minor updates:

Code:

append () {
IFS="|"
found=0
while read factor trial
do
  if [ "$factor" = "$1" ] 
  then
    echo "$factor|$trial|$2"
    found=1
  else
    echo "$factor|$trial"
  fi
done < file > file.new
if [ $found = 0 ]
then
    echo "$1|$2" >> file.new
fi
}

Code:

awk -F"|" '{if ($1==factor) {print $0 FS trial;found=1} else {print}END{if(! found) print factor FS trial}' factor="3,6" trial="YES,18,1.635" < file > file.new

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