如何将行从一个文件替换/添加到另一个文件

Question

I have a one file like below example and I have requirement to grep the lines which are starting with system_props( cat file1 | grep ^system_props )..

JAVA_HOME=`find "$AGENT_HOME/jre" -name release -type f 2>/dev/null | sed "s|/release||g"`

system_props="$system_props -sensu.controller.hostName=abc.nam.net"
system_props="$system_props -sensu.controller.port=8181"
system_props="$system_props -sensu.controller.node=Mcagent"

if [ -z "$JAVA_HOME" ]; then
   if [ -d "/opt/middleware" ]; then
      JAVA_HOME=`find /opt/middleware -type d -name jre 2>/dev/null | grep WebSphere | grep java | grep -v grep | sort | uniq`
   fi
fi

I have another file called say file2 which having dummy content like below.

JAVA_HOME=`find "$AGENT_HOME/jre" -name release -type f 2>/dev/null | sed "s|/release||g"`

system_props="$system_props -sensu.controller.hostName=testhost.net"
system_props="$system_props -sensu.controller.port=8080"

if [ -z "$JAVA_HOME" ]; then
   if [ -d "/opt/middleware" ]; then
      JAVA_HOME=`find /opt/middleware -type d -name jre 2>/dev/null | grep WebSphere | grep java | grep -v grep | sort | uniq`
   fi
fi

Now my requirement is to replace the content of cat file1 | grep ^system_propscat file1 | grep ^system_props to cat file2 | grep ^system_props) cat file2 | grep ^system_props)

The expected output of the system_props lines should be added in the file2 which are in file1 under same sequence.

system_props="$system_props -sensu.controller.hostName=abc.nam.net"
system_props="$system_props -sensu.controller.port=8181"
system_props="$system_props -sensu.controller.node=Mcagent"

Answer 1

Could you please try following. Written and tested with samples.

awk '
FNR==NR{
  if(match($0,/system_props="/)){
    val=(val?val ORS:"")$0
  }
  next
}
/^system_props="/{
  if(++count==1){
    print val
  }
next
}
1
'  Input_file1   Input_file2

Explanation: Adding detailed explanation for above code.

awk '                                ##Starting awk program from here.
FNR==NR{                             ##Checking condition FNR==NR which will be TRUE when Input_file1 is being read.
  if(match($0,/system_props="/)){    ##Checking condition if match for string system_props=" is found in current line then do following.
    val=(val?val ORS:"")$0           ##Creating variable val and keep appending current line value to its value here.
  }
  next                               ##next will skip all further statements from here.
}
/^system_props="/{                   ##Checking condition if line is starting from sting system_props=" then do following.
  if(++count==1){                    ##Checking condition if variable count is 1 then do following.
    print val                        ##Printing val variable here.
  }
  next                               ##next will skip all further statements from here.
}
1                                    ##1 will print edited/non-edited line here.
'  file1  file2                      ##Mentioning Input_file names here.

Answer 2

I gave this a go without looking at the existing answers and came up with roughly the same answer as Ravinder.

awk '
FNR == NR  { 
  line[FNR] = $0 
  next 
}  
/^system_props/  { 
  if (!nocopy) 
    for (x = 0 ; x < length(line) ; x++ ) 
      print line[x]  
  nocopy=1 
  next 
} 
{ 
  print 
} '  <( grep ^system_props file1 )  file2

Personally, I like Ravinder's solution better. His count variable is the same as my nocopy variable. And he uses a single variable to capture the system_props from the first file whereas I use an array.

Also, Ravinder is looking for "^system_props" lines within awk, whereas I relegate that responsibility to grep. However, some may feel that the <( ) syntax I'm using for the grep may be unnecessarily complex.

I also noticed that Ravinder used an awk idiom of 1 to indicate always print which is equivalent to the what I spelled out with {print} . I like Ravinder's approach because it's shorter (albeit perhaps less obvious to the reader).

Answer 3

You want to concatenate three file segments:
1. The second file until the first ^system_props
2. The lines from the first file with ^system_props
3. The second file after the last ^system_props

# Part 1
sed '/^system/,$ d' file2
# Part 2
grep '^system' file1
# Or sed -n '/^system/p' file1
# Part 3
sed '1,/^system/d; /^system/ d' file2

Together:

sed '/^system/,$ d' file2; grep '^system' file1; sed '1,/^system/d; /^system/ d' file2

This approach can be done with awk too:

awk -F= 'BEGIN {show=1}
         ARGIND==1 && $1=="system_props" {show=0}
         ARGIND==2 {show=($1=="system_props" ? 1:0)}
         ARGIND==3 && $1=="system_props" {show=1; next}
         show {print}' file2 file1 file2