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Accepted
Seninha
Asked: 2019-04-29 21:16:11 +0800 CST

复制行并使用 sed 或 awk 将其插入新位置

  • 772

我有这个文件：

a
b
c
d
e
f

我希望将最后一行复制到第一行之前，所以我会得到以下结果：

f
a
b
c
d
e
f

我怎样才能在sedor中做到这一点awk？

awk text-processing

8 个回答

  1. With ed:

    $ printf '$t0\n,p\n' | ed -s file
f
a
b
c
d
e
f

    The t command in ed transfers/copies a line from the addressed line (here $ for the last line) to after the line addressed by its argument (here 0, i.e. insert before the first line). The ,p command prints the contents of the editing buffer (change this to w to write the result back into the file).

    • 10

  2. 或者只是像这样，没有 sed 或其他

    tail -1 list && cat list
    • 9
  3. Best Answer

    纯sed：

    sed 'H;1h;$!d;G' file.txt

    所有行都收集在保持空间中，然后附加到最后一行：

    • H appends the current line to the hold space. Unfortunally this will start the hold space with a newline, so 1h for the first line, the hold space gets overwritte with that line without preceeding newline
    • $!d means if this is not (!) the last line ($), delete the line, because we don't want to print it yet
    • G is only executed for the last line, because for other lines the d stopped processing. Now all lines (first to last) we collected in the hold space get appended to the current (last) line with the G command and everything gets printed at the end of the script.
    • 9

  4. 另一种sed选择是：

    sed '$!d; r infile' infile

    删除除最后一个，下一个读取和输出整个文件之外的所有行。

    • 8

  5. GNU awk:

    awk 'ENDFILE { if(NR==FNR) print } NR!=FNR' infile{,}

    Portable awk:

    awk 'NR!=FNR && !f { f=1; print p } NR!=FNR; { p=$0 }' infile{,}
    • 3

  6. Reverse the file, remember the first line and print it after the last line, then re-reverse the file:

    tac file | awk 'FNR == 1 {last=$0} {print} END {print last}' | tac
# or
tac file | sed -n '1h; p; ${x;p}' | tac
    • 2

  7. Tried with below sed command and it worked fine too

    command

    k=`sed -n '$p' filename `
sed '1i '$k'' filename

    output

    f
a
b
c
d
e
f
    • 2

  8. 尝试这个，

     tail -n1 file | xargs -I '{}' sed '1i{}' file
    • tail -n1将打印文件的最后一行
    • xargs -I将尾部输出传递给 sed
    • sed '1i将在第一行插入上下文

    如果输出看起来是文件，则-i向 sed 添加选项以进行内联编辑

    • 1

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