你需要先检查你是否遇到了字符串xyz。如果你遇到了，那么设置一个标志为true。然后继续读取文件。如果读取的前一行是xyz，那么标志将被设置为True。检查当前行是否有mpe，并将该行附加到lines。看看这段代码是否有效。

str1_name ="* xyz"  
str2_name = "mpe:" 
prev_xyz = False

lines = [] 

with open("textfile.txt",'r') as f:
    for line in f:
       if str2_name in line and prev_xyz:
           lines.append(line.strip())  
           #lines2=lines[0] prev line will strip out \n
       if str1_name in line:
           prev_xyz = True
       else:
           prev_xyz = False
print(lines)

输出：

['4 mpe:p04']

好吧，如果你确定 mpe 跟在 xyz 后面，你可以运行如下代码：

str1_name ="* xyz"  

with open("textfile.txt",'r') as f:
    for line in f:
        while str1_name not in line:
            pass
        if str2_name in line:
            print(next(f))

如果搜索的字符串没有紧跟在后面：

str1_name ="* xyz"
str2_name = "mpe:"  

checkpoint = False

with open("textfile.txt",'r') as f:
    for line in f:
        if str1_name in line:
            checkpoint = True
        if checkpoint and str2_name in line:
            print(line)
            break

lines = []
line_after_str1=[]

str1_name ="* xyz"

str2_name = "mpe:" 

with open("textfile.txt",'r') as f:
    all_lines=f.readlines()
    for line in range(len(all_lines)):
        
        if str1_name in all_lines[line]:
            line_after_str1.append(all_lines[line+1].replace('\n',''))
        elif str2_name in all_lines[line]:
            lines.append(all_lines[line].replace('\n',''))
        

print(line_after_str1)

输出：

['4 mpe:p04']