Vikram，如果您的实际 Input_file 与显示的示例 Input_file 相同，那么以下内容可能对您有所帮助。我很快也会在这里添加解释（使用 GNU awk 3.1.7 小旧版本的 awk 对此进行了测试）。
awk -v num="2,3" 'BEGIN{
len=split(num, val,",")
}
{while($0){
match($0,/.[^"]*/);
if(substr($0,RSTART,RLENGTH+1) && substr($0,RSTART,RLENGTH+1) !~ /\"\| \"/ && substr($0,RSTART,RLENGTH+1) !~ /^\"$/ && substr($0,RSTART,RLENGTH+1) !~ /^\" \"$/){
array[++i]=substr($0,RSTART,RLENGTH+1)
};
$0=substr($0,RLENGTH+1);
};
for(l=1;l<=len;l++){
delete array[val[l]]
};
for(j=1;j<=length(array);j++){
if(array[j]){
gsub(/^\"|\"$/,"",array[j]);
printf("%s%s",array[j],j==length(array)?"":" ")
}
};
print "";
i="";
delete array
}' Input_file
EDIT1：在这里也添加一个带有解释的代码。
awk -v num="2,3" 'BEGIN{ ##creating a variable named num whose value is comma seprated values of fields which you want to nullify, starting BEGIN section here.
len=split(num, val,",") ##creating an array named val here whose delimiter is comma and creating len variable whose value is length of array val here.
}
{while($0){ ##Starting a while loop here which will run for a single line till that line is NOT getting null.
match($0,/.[^"]*/);##using match functionality which will look for matches from starting to till a " comes into match.
if(substr($0,RSTART,RLENGTH+1) && substr($0,RSTART,RLENGTH+1) !~ /\"\| \"/ && substr($0,RSTART,RLENGTH+1) !~ /^\"$/ && substr($0,RSTART,RLENGTH+1) !~ /^\" \"$/){##So RSTATR and RLENGTH are the variables which will be set when a regex is having a match in line/variable passed into match function. In this if condition I am checking 1st: value of substring of RSTART,RLENGTH+1 should not be NULL. 2nd: Then checking this substring should not be having " pipe space ". 3rd condition: Checking if substring is NOT equal to a string which starts from " and ending with it. 4th condition: Checking here if substring is NOT equal to ^" space "$, if all conditions are TRUE then do following actions.
array[++i]=substr($0,RSTART,RLENGTH+1) ##creating an array named array whose index is variable i with increasing value of i and its value is substring of RSTART to till RLENGTH+1.
};
$0=substr($0,RLENGTH+1);##Now removing the matched part from current line which will decrease the length of line and avoid the while loop to become as infinite.
};
for(l=1;l<=len;l++){##Starting a loop here once while above loop is done which runs from starting of variable l=1 to value of len.
delete array[val[l]] ##Deleting here those values which we want to REMOVE from OPs request, so removing here.
};
for(j=1;j<=length(array);j++){##Start a for loop from the value of j=1 till the value of lengthh of array.
if(array[j]){ ##Now making sure array value whose index is j is NOT NULL, if yes then perform following statements.
gsub(/^\"|\"$/,"",array[j]); ##Globally substituting starting " and ending " with NULL in value of array value.
printf("%s%s",array[j],j==length(array)?"":" ") ##Now printing the value of array and secondly printing space or null depending upon if j value is equal to array length then print NULL else print space. It is because we don not want space at the last of the line.
}
};
print ""; ##Because above printf will NOT print a new line, so printing a new line.
i=""; ##Nullifying variable i here.
delete array ##Deleting array here.
}' Input_file ##Mentioning Input_file here.