这让我非常恼火，我坐下来写了一个类似cut的字段规范解析器，用GNU Awk 3.1.7测试。

首先，创建一个新的Awk库脚本pfcut。

sudo nano /usr/share/awk/pfcut

然后，粘贴下面的脚本，并保存。之后，是这样的用法:

$ echo "t1 t2 t3 t4 t5 t6 t7" | awk -f pfcut --source '/^/ { pfcut("-4"); }'
t1 t2 t3 t4

$ echo "t1 t2 t3 t4 t5 t6 t7" | awk -f pfcut --source '/^/ { pfcut("2-"); }'
t2 t3 t4 t5 t6 t7

$ echo "t1 t2 t3 t4 t5 t6 t7" | awk -f pfcut --source '/^/ { pfcut("-2,4,6-"); }'
t1 t2 t4 t6 t7

为了避免键入所有这些，我想最好的方法是(参见其他方法)在启动时自动加载用户函数?- Unix & Linux Stack Exchange)为~/.bashrc添加别名;例如:

$ echo "alias awk-pfcut='awk -f pfcut --source'" >> ~/.bashrc
$ source ~/.bashrc     # refresh bash aliases

．.． 然后你可以调用:

$ echo "t1 t2 t3 t4 t5 t6 t7" | awk-pfcut '/^/ { pfcut("-2,4,6-"); }'
t1 t2 t4 t6 t7

以下是pfcut脚本的源代码:

# pfcut - print fields like cut
#
# sdaau, GNU GPL
# Nov, 2013

function spfcut(formatstring)
{
  # parse format string
  numsplitscomma = split(formatstring, fsa, ",");
  numspecparts = 0;
  split("", parts); # clear/initialize array (for e.g. `tail` piping into `awk`)
  for(i=1;i<=numsplitscomma;i++) {
    commapart=fsa[i];
    numsplitsminus = split(fsa[i], cpa, "-");
    # assume here a range is always just two parts: "a-b"
    # also assume user has already sorted the ranges
    #print numsplitsminus, cpa[1], cpa[2]; # debug
    if(numsplitsminus==2) {
     if ((cpa[1]) == "") cpa[1] = 1;
     if ((cpa[2]) == "") cpa[2] = NF;
     for(j=cpa[1];j<=cpa[2];j++) {
       parts[numspecparts++] = j;
     }
    } else parts[numspecparts++] = commapart;
  }
  n=asort(parts); outs="";
  for(i=1;i<=n;i++) {
    outs = outs sprintf("%s%s", $parts[i], (i==n)?"":OFS); 
    #print(i, parts[i]); # debug
  }
  return outs;
}

function pfcut(formatstring) {
  print spfcut(formatstring);
}

在这里给出的所有其他答案以及在相关问题中给出的各种可能的FS值都以各种方式失败。有些在开头和/或结尾留下空白，有些将每个FS转换为OFS，有些依赖于仅当FS为默认值时才适用的语义，有些依赖于在括号表达式中否定FS，这将在给定多字符FS时失败，等等。

为了对任何FS都健壮地做到这一点，使用GNU awk的第4个参数split():

$ cat tst.awk
{
    split($0,flds,FS,seps)
    for ( i=n; i<=NF; i++ ) {
        printf "%s%s", flds[i], seps[i]
    }
    print ""
}

$ printf 'a b c d\n' | awk -v n=3 -f tst.awk c d $ printf ' a b c d\n' | awk -v n=3 -f tst.awk c d $ printf ' a b c d\n' | awk -v n=3 -F'[ ]' -f tst.awk b c d $ printf ' a b c d\n' | awk -v n=3 -F'[ ]+' -f tst.awk b c d $ printf 'a###b###c###d\n' | awk -v n=3 -F'###' -f tst.awk c###d $ printf '###a###b###c###d\n' | awk -v n=3 -F'###' -f tst.awk b###c###d Note that I'm using split() above because it's 3rg arg is a field separator, not just a regexp like the 2nd arg to match(). The difference is that field separators have additional semantics to regexps such as skipping leading and/or trailing blanks when the separator is a single blank char - if you wanted to use a while(match()) loop or any form of *sub() to emulate the above then you'd need to write code to implement those semantics whereas split() already implements them for you.

zed_0xff投票最多的答案不适合我。

我有一个日志，其中$5与IP地址可以是更多的文本或没有文本。我需要从IP地址到行尾的所有内容，如果有任何在$5之后。在我的例子中，这实际上是在一个awk程序中，而不是awk一行程序，因此awk必须解决这个问题。当我试图删除前4个字段使用zed_0xff提出的解决方案:

echo "  7 27.10.16. Thu 11:57:18 37.244.182.218" | awk '{$1=$2=$3=$4=""; printf "[%s]\n", $0}'

它吐出错误和无用的回应(我添加了[..]以示范):

[    37.244.182.218 one two three]

甚至有人建议将substr与这个错误的答案结合起来，但这只会使事情复杂化。它没有提供任何改进。

相反，如果列的宽度是固定的，直到需要切割点和awk，正确答案是:

echo "  7 27.10.16. Thu 11:57:18 37.244.182.218" | awk '{printf "[%s]\n", substr($0,28)}'

它产生所需的输出:

[37.244.182.218 one two three]

这让我非常恼火，我坐下来写了一个类似cut的字段规范解析器，用GNU Awk 3.1.7测试。

首先，创建一个新的Awk库脚本pfcut。

sudo nano /usr/share/awk/pfcut

然后，粘贴下面的脚本，并保存。之后，是这样的用法:

$ echo "t1 t2 t3 t4 t5 t6 t7" | awk -f pfcut --source '/^/ { pfcut("-4"); }'
t1 t2 t3 t4

$ echo "t1 t2 t3 t4 t5 t6 t7" | awk -f pfcut --source '/^/ { pfcut("2-"); }'
t2 t3 t4 t5 t6 t7

$ echo "t1 t2 t3 t4 t5 t6 t7" | awk -f pfcut --source '/^/ { pfcut("-2,4,6-"); }'
t1 t2 t4 t6 t7

为了避免键入所有这些，我想最好的方法是(参见其他方法)在启动时自动加载用户函数?- Unix & Linux Stack Exchange)为~/.bashrc添加别名;例如:

$ echo "alias awk-pfcut='awk -f pfcut --source'" >> ~/.bashrc
$ source ~/.bashrc     # refresh bash aliases

．.． 然后你可以调用:

$ echo "t1 t2 t3 t4 t5 t6 t7" | awk-pfcut '/^/ { pfcut("-2,4,6-"); }'
t1 t2 t4 t6 t7

以下是pfcut脚本的源代码:

# pfcut - print fields like cut
#
# sdaau, GNU GPL
# Nov, 2013

function spfcut(formatstring)
{
  # parse format string
  numsplitscomma = split(formatstring, fsa, ",");
  numspecparts = 0;
  split("", parts); # clear/initialize array (for e.g. `tail` piping into `awk`)
  for(i=1;i<=numsplitscomma;i++) {
    commapart=fsa[i];
    numsplitsminus = split(fsa[i], cpa, "-");
    # assume here a range is always just two parts: "a-b"
    # also assume user has already sorted the ranges
    #print numsplitsminus, cpa[1], cpa[2]; # debug
    if(numsplitsminus==2) {
     if ((cpa[1]) == "") cpa[1] = 1;
     if ((cpa[2]) == "") cpa[2] = NF;
     for(j=cpa[1];j<=cpa[2];j++) {
       parts[numspecparts++] = j;
     }
    } else parts[numspecparts++] = commapart;
  }
  n=asort(parts); outs="";
  for(i=1;i<=n;i++) {
    outs = outs sprintf("%s%s", $parts[i], (i==n)?"":OFS); 
    #print(i, parts[i]); # debug
  }
  return outs;
}

function pfcut(formatstring) {
  print spfcut(formatstring);
}

我想把建议的答案扩展到字段可能由几个空格分隔的情况——我想这就是OP不使用cut的原因。

我知道OP问了关于awk的问题，但sed方法在这里可以工作(例如从第5列打印到最后一列):

pure sed approach sed -r 's/^\s*(\S+\s+){4}//' somefile Explanation: s/// is the standard command to perform substitution ^\s* matches any consecutive whitespace at the beginning of the line \S+\s+ means a column of data (non-whitespace chars followed by whitespace chars) (){4} means the pattern is repeated 4 times. sed and cut sed -r 's/^\s+//; s/\s+/\t/g' somefile | cut -f5- by just replacing consecutive whitespaces by a single tab; tr and cut: tr can also be used to squeeze consecutive characters with the -s option. tr -s [:blank:] <somefile | cut -d' ' -f5-

打印从#2开始的列(输出在开始时没有尾随空格):

ls -l | awk '{sub(/[^ ]+ /, ""); print $0}'