bash脚本需要多个文件中的行bash

Question

我需要一个Shell脚本来设计为以三个文件中的模式打印行。

file1.txt, file2.txt,file3.txt

我需要输出

line1 of file1.txt
line2 of file1.txt
line1 of file2.txt
line2 of file2.txt
line1 of file3.txt
line2 of file3.txt
line3 of file1.txt
line4 of file1.txt
line3 of file2.txt
line4 of file2.txt
line3 of file3.txt
line4 of file3.txt

...

我们如何在shell脚本中得到它？ 另外，它应该只打印非空白行。

Answer 1

Perl解救：

perl -e 'open $FH[ @FH ], "<", $_ or die $! for @ARGV;
         while (grep !eof $_, @FH) {
             for my $fh (@FH) {
                 print scalar <$fh> for 1, 2;
             }
         }' -- file*.txt

它使所有文件同时打开（@FH数组包含文件句柄）。 尽管至少有一个尚未结束，但每行都打印了两行。

Answer 2

下面的脚本呢，该脚本接受文件作为参数：

TOTAL_LINES=$(wc -l < "$1")
for n in $(seq 1 2 $TOTAL_LINES); do
  for file in "$@"; do
    sed -n "$n{p;n;p}" $file
  done
done

我认为所有文件的行数都与注释中建议的相同，但是如果情况并非如此，只要您将最长的文件作为第一个参数传递，它也可以工作。

对您不太可能了解的脚本部分进行一些解释：

• seq将生成一个数字序列以for迭代。 它的语法是seq from increment upTo到seq from increment upTo的语法，用于代替不接受变量的{from..upTo..increment}语法
• $@是传递给脚本的参数数组
• sed -n "$n{p;n;p}"是sed命令，默认情况下不会显示文本，但是将对$n行再次执行p ， n和p ； p打印当前行， n转到下一行

Answer 3

考虑四个类似的输入文件：

$ cat file1.txt
line1 of file1.txt
line2 of file1.txt
line3 of file1.txt
line4 of file1.txt

我们按如下方式创建printer.sh ：

#!/bin/bash
LINES=2 # Configure this to set the number of consecutive lines per file

MAX_HANDLE=3
# Create descriptors 3,4,... for filename1,filename2....
for var in "$@"
do
      eval exec "$MAX_HANDLE"'<"$var"'
      ((MAX_HANDLE++))
done

# Start infinite loop
while :
do
  # First descriptor is 3
  COUNTER=3

  # Loop over all open file descriptors from 3 to MAX_HANDLE - 1
  while [  $COUNTER -lt $MAX_HANDLE ]; do
    # Read $LINES lines from the open file descriptor
    LINE_COUNTER=0
    while [  $LINE_COUNTER -lt $LINES ]; do
      read -r line <&"$COUNTER" || DONE=true
      if [[ "$DONE" = true ]]; then
        exit
      fi


      # Print the line that was read
      echo "$line"
      ((LINE_COUNTER++))
    done
    ((COUNTER++))
  done
done

执行此操作时，每个输入参数都添加到一个新的句柄中，并一次读取$LINES行（在这种情况下，一次读取2行）。 这仅适用于与OP存放长度相同的文件。

$ ./printer.sh file1.txt file2.txt file3.txt file4.txt
line1 of file1.txt
line2 of file1.txt
line1 of file2.txt
line2 of file2.txt
line1 of file3.txt
line2 of file3.txt
line1 of file4.txt
line2 of file4.txt
line3 of file1.txt
line4 of file1.txt
line3 of file2.txt
line4 of file2.txt
line3 of file3.txt
line4 of file3.txt
line3 of file4.txt
line4 of file4.txt

Answer 4

您可以将awk与paste一起使用以获取输出：

paste -d $'\01' file[123].txt |
awk -F '\01' 'NR%2{for (i=1; i<=NF; i++) a[i]=$i; next} 
    {for (i=1; i<=NF; i++) print a[i] ORS $i}'

line1 of file1.txt
line2 of file1.txt
line1 of file2.txt
line2 of file2.txt
line1 of file3.txt
line2 of file3.txt
line3 of file1.txt
line4 of file1.txt
line3 of file2.txt
line4 of file2.txt
line3 of file3.txt
line4 of file3.txt

• 使用paste我们创建并排control-A （ASCII 1）定界输出
• 使用带有字段分隔符的awk作为control-A我们从每列输出2行

Answer 5

很多答案。 这个是awk

创建测试文件

for f in file{1,2,3}.txt; do rm $f; for n in {1,2,3,4}; do echo "line $n of file $f" >> $f; done; done

和awk程序

awk '
    FNR == 1 && NR>1 {
        exit # exit after completing the first file
    }
    {
        # print 2 lines from the first file
        if (NF) print
        getline; if (NF) print
        # print 2 lines from each other file
        for (i=2; i<ARGC; i++) {
            getline < ARGV[i]; if (NF) print
            getline < ARGV[i]; if (NF) print
        }
    }
' file{1,2,3}.txt

if (NF) print行排除空白行，因为用空格分隔的字段数将为零。

line 1 of file file1.txt
line 2 of file file1.txt
line 1 of file file2.txt
line 2 of file file2.txt
line 1 of file file3.txt
line 2 of file file3.txt
line 3 of file file1.txt
line 4 of file file1.txt
line 3 of file file2.txt
line 4 of file file2.txt
line 3 of file file3.txt
line 4 of file file3.txt

Answer 6

这可能不是最有效的方法，但如果您将所有文件都放在$ files中，并且$ total_lines包含每个文件中的行数，则该方法将起作用：

for line in $(seq 1 $total_lines)
do
    for file in $files
    do
        sed '/^$/d' $file | sed $line'!d'
    done
done

sed'/ ^ $ / d'从流中删除所有空行；

sed $ line'！d'打印出与$ line相对应的行

Answer 7

使用粘贴和awk。

$ cat test.sh 
paste -d '|' file* | awk -F\| '{
    if(NR % 2 == 1) {
        file1 = $1; 
        file2 = $2; 
        file3 = $3; 
    } else {
        file1 = file1 "\n" $1; 
        file2 = file2 "\n" $2; 
        file3 = file3 "\n" $3; 
        print file1;
        print file2;
        print file3;
    }
}'

由于所有文件的长度相同，因此我们可以先粘贴所有文件，然后在行数为偶数时打印。

Answer 8

如果您不介意创建中间/临时文件，则每个Linux发行版coreutils的一部分split（1）可能会很方便：

#!/bin/bash

# Split files every 2 lines using a numeric suffix 
for f in file*.txt; do
    split -d -l 2 "${f}" "${f}"split
done

# Reverse intermediate file names, so we can glob them in numeric order 
for f in file*split*; do
    mv "${f}" "reversed$(echo ${f}|rev)"
done

cat reversed* && rm reversed*