这是一种实现方式：

$ awk '
NR==FNR {                  # process file1
    if(FNR==1)             # print header,no newline
        printf $1
    a[$1]                  # hash data
    next
}
{                          # process file2
    if(FNR==1)             # print the other half of the header
        print OFS $2
    for(i in a)            # loop all items in hash
        if($1 ~ i)         # check for partial match
            print i,$2     # if found,output
}' file1 file2             # mind the order

输出（按照file2的顺序，注意输出的最后一行的部分匹配，作为警告留在这里）：

ID category
479432_Sros_4274 P
257310_BB0482 J
517722_CJLT1_010100003977 U
330214_NIDE2792 S
ID S

请您尝试以下。

awk '
BEGIN{
  print "ID  category"
}
FNR==NR{
  a[$0]
  next
}
{
  for(i in a){
    if(match($0,i)){
      print i,$NF
    }
  }
}
'  Input_filea   Input_fileb

说明： 添加上述代码的说明。

awk '                               ##Starting awk program here.
BEGIN{                              ##Starting BEGIN section from here.
  print "ID  category"              ##Printing string ID,category here.
}                                   ##Closing BLOCK for BEGIN section.
FNR==NR{                            ##Checking condition FNR==NR which will be TRUE when 1st Input_file is being read.
  a[$0]                             ##Creating an array named a whose index is $).
  next                              ##next will skip all further statements from here.
}
{
  for(i in a){                      ##Traversing through array a with for loop.
    if(match($0,i)){                ##Checking condition if match is having a proper regex matched then do following.
      print i,$NF                   ##Printing variable i and $NF of current line.
    }
  }
}
'  Input_filea   Input_fileb        ##Mentioning Input_file names here.