使用命令行工具合并2个文件

Question

我是2个csv文件，如下所示：

id, name, job
1, bob, fireman
3, alice, nurse
7, peter, policeman
...

和：

id, name, age
2, john, 26
4, craig, 32
5, mary, 45
6, lucy, 23
...

如您所见，它们都是按in排序的，而第一个csv中缺少的in实际上在第二个csv中。

是否可以通过命令行工具(如awk )或类似的工具将这2 csv合并成如下所示的命令行工具？

id, name, job, age
1, bob, fireman,
2, john, , 26
3, alice, nurse,
4, craig, , 32
...

非常感谢你的帮助？

Answer 1

这应该可以做到：

awk -F, -v OFS=, 'FNR==NR && FNR>1 {a[$1]=$0;c++;next} FNR>1{$NF=" ,"$NF;a[$1]=$0;c++} END {print "id, name, job, age";for (i=1;i<=c;i++) print a[i]}' file1 file2
id, name, job, age
1, bob, fireman
2, john, , 26
3, alice, nurse
4, craig, , 32
5, mary, , 45
6, lucy, , 23
7, peter, policeman

它的工作原理：

awk -F, -v OFS=, '              # Set input and output Field separator to ","
FNR==NR && FNR>1 {              # For first file except first record do:
    a[$1]=$0                    # Store records inn to array "a"
    c++                         # Increment "c" for every record
    next}                       # Skip to next record
FNR>1 {                         # For second file except first record do:
    $NF=" ,"$NF                 # Replace last record with an extra ","
    a[$1]=$0                    # Store records inn to array "a"
    c++}                        # Increment "c" for every record
END {                           # When all file is read do:
    print "id, name, job, age"  # Print header
    for (i=1;i<=c;i++)          # Loop "c" times
        print a[i]}             # Print records
' file1 file2                   # Read the files

在读取多个文件以区分要处理的文件时，经常使用FNR==NR。