使用 AWK 减去时间

Question

我想要实现的是第 1 章开始时间和第 2 章开始时间之间的差异，依此类推，从数组中的下一章开始时间减去每个章节开始时间，例如 00:05:57 - 00:01:03 = 00:04 :54

$ cat ChapterStart 
00:00:00 00:01:03 00:05:57 00:08:27 00:11:58 00:14:50 00:20:19 00:25:06 00:33:17 00:38:21 00:42:30 00:46:11 00:51:33 01:00:04 01:00:56 01:04:15 01:09:13 01:16:51 01:20:03 01:27:58

这根本行不通：

#!/bin/bash
awk 'BEGIN{
{
 for(i=1;i<=NF;i++){
    m=split($i,t,":")
    n=split($(i+1),w,":")
    chap = (t[1]*3600) + (t[2]*60) + t[3]
    chap_next = (w[1]*3600) + (w[2]*60) + w[3]
    duration = (chap_next - chap)
    print $duration
    }
 }
}'ChapterStart

有什么建议吗？

Answer 1

问题是您在 BEGIN 块中运行整个过程，因此它永远看不到数据。只需删除“BEGIN{”和最后一个“}”，它就应该可以正常工作。

BEGIN 块在读取任何数据之前运行，并用于初始化。 awk 程序结构如下所示（BEGIN，主数据循环 - 由一个或多个块组成 - 和 END 都是可选的）：

BEGIN { 
}
{
}
END {
}

主循环中的程序块可以有各种条件表达式、正则表达式或模式来选择是否执行它们。

另外，您的循环需要在最后一个字段之前停止，因为它无法获取最后一个字段之后的下一个字段：

for(i=1;i<NF;i++){

除非您删除美元符号，否则这一行将不起作用：

    print $duration

因为您没有对返回值执行任何操作split 您可以消除变量分配或重用变量：

split($i,t,":")
split($(i+1),w,":")

或者

m=split($i,t,":")
m=split($(i+1),w,":")

此外，当您发布问题“不起作用”时，信息量并不大。

Answer 2

正确的代码应该是

awk '{
 for(i=1;i<NF;i++){
    m=split($i,t,":")
    n=split($(i+1),w,":")
    chap = (t[1]*3600) + (t[2]*60) + t[3]
    chap_next = (w[1]*3600) + (w[2]*60) + w[3]
    duration = (chap_next - chap)
    print duration
 }
}' file

在 awk 读取输入文件之前处理 BEGIN 块。因此，如果您将代码放在 BEGIN 块内，则该文件将不会被处理。

Answer 3

此外，当您发布问题时
“不起作用”并没有提供太多信息。

你当然是对的。也许最好说“什么也不做”，这会非常准确，因为实际上什么也没发生。 =)

谢谢你们俩。

虽然我还没有完全理解 awk 的许多神秘方式，但我确实找到了一个更简单的（对我来说）解决方案，并在这个过程中学到了一些东西。这可行，但肯定可以做得更好。

#!/bin/bash
#~ Prelude to a DVD audio ripper.
#~ This simply prints Audio ID's & start/end/duration times for the longest DVD title. 

MPLAYER=$(which mplayer)
DRIVE=${1:-/dev/dvd} ## Check for softlink to DVD drive, otherwise let user specify
    if ! [ -b "$DRIVE" ]; then 
        read -p "DVD drive name? (/dev/scd0 for example): " DRIVE
    fi

#~ Find, then scan the longest title

    LTITLE=$($MPLAYER dvd:// -dvd-device $DRIVE -identify -vo null -ao null -nolirc -nojoystick \
    -frames 0 2>/dev/null| awk '/ID_DVD_TITLE/'|awk '/LENGTH/'|sort -n -t = -k 2 |tail -1 |cut -f 4 -d _)
    MPLAYER_OUT=$($MPLAYER dvd://$LTITLE -dvd-device $DRIVE -identify -vo null -ao null -nolirc \
    -nojoystick -frames 0 2>/dev/null) ## mplayer tells us about the longest title on the disc/image

#~ Set some variables per $MPLAYER_OUT 

    VID=$(echo "$MPLAYER_OUT"|awk '/ID_DVD_VOLUME_ID=/{sub(/ID_DVD_VOLUME_ID=/,"");print}') ## Get the DVD Volume ID
    CHAPTERS=$(echo "$MPLAYER_OUT"|awk '/ID_CHAPTERS/ {sub(/ID_CHAPTERS=/,"");print}') ## Total number of chapters in longest title
    ChapStart=($(echo "$MPLAYER_OUT"|awk '/CHAPTERS:/'|sed 's/CHAPTERS://; s/,/\n /g'))
    ChapEnd=($(echo "$MPLAYER_OUT"|awk '/CHAPTERS:/'|sed 's/CHAPTERS://; s/,/\n /g')) 
    DiscTimeTotal=$(echo "$MPLAYER_OUT" |awk '/ID_DVD_TITLE_'$LTITLE'_LENGTH/ {sub(/ID_DVD_TITLE_'$LTITLE'_LENGTH=/,"");print}')
    DiscTime=$(echo "$MPLAYER_OUT" |echo - |awk '{printf "%02d:%02d:%02d","'"$DiscTimeTotal"'"/(60*60),"'"$DiscTimeTotal"'"%(60*60)/60,"'"$DiscTimeTotal"'"%60}';echo) ## Converted to HH:MM:SS
    Disc=$(date +%s -d "$DiscTime") ## Convert to seconds since 1970-01-01 - this becomes that last ChapTimeEnd array element
    Streams=$(echo "$MPLAYER_OUT" |awk '/audio stream/'|sed 's/.$//;s/language/Language/'|awk '{ print "AID: " $10, "Format: " $5, $7, $8, $6 }')

#~ Convert ChapStart HH:MM:SS to ChapTimeStart seconds since 1970-01-01 

for ((s=0; s<=$CHAPTERS; s++)) 
    do 
        ChapTimeStart[$s]=$(date +%s -d "${ChapStart[$s]}") 
        ChapTimeEnd[$s]=$(date +%s -d "${ChapEnd[$s]}")
done

    unset ChapTimeEnd[0] ## Remove the first chapter start time (always 00:00:00) in the array
    ChapTimeEnd[$CHAPTERS]=$Disc ## Add $Disc as last array element
    ChapTimeEnd=( "${ChapTimeEnd[@]}" ) ## Pack the array

    unset ChapEnd[0] ## Offset the time differences - this is printed to screen as "End: HH:MM:SS"
    ChapEnd[$CHAPTERS]=$DiscTime ## Add $DiscTime as last array element
    ChapEnd=( "${ChapEnd[@]}" )     ## Pack the array

#~ Provide some feedback:

echo
echo "  --- DVD Volume ID ---";echo
echo "$VID";echo
echo "  --- Longest Title ----";echo
echo "Title $LTITLE is longest with $CHAPTERS Chapters"
echo "Title $LTITLE Length: $DiscTime";echo
echo "  ---- Audio ID's ----";echo
echo "$Streams";echo

#~ Print start/end/duration

echo "  ---- Chapters ----";echo
 for ((t=0; t<$CHAPTERS; t++)) 
    do TimeDiff[$t]=$((${ChapTimeEnd[$t]} - ${ChapTimeStart[$t]}))  ## Do the integer math with values expressed as seconds since 1970-01-01 
        Duration=$(echo - |awk '{printf "%02d:%02d:%02d","'"${TimeDiff[$t]}"'"/(60*60),"'"${TimeDiff[$t]}"'"%(60*60)/60,"'"${TimeDiff[$t]}"'"%60}';echo)
    echo "Chapter: `printf "%02d" $(($t+1))`  Start: "${ChapStart[$t]}" End: "${ChapEnd[$t]}" Duration: $Duration"
 done 
 echo "_____________________________________________________________"
echo

Answer 4

其他解决方案仍然一遍又一遍地重新分割相同的列。该方法一次性分割整个输入，假设每个值都是正确的 HH:MM:SS，然后从左到右迭代它们，并将每个 chap_next 保存为下一个周期的chap：

---

awk '
function ______(__, _, ___, ____, _____) {

    gsub(/:/, _ = " ", __)
    ____ = (__ = (_ += _ = (_____ = split(__, ___, _))^_) * \
           (++_^_ + _--)) * (__ * ___[!!_] + ___[_]) + ___[++_]

    while (_++ < _____)
        print " duration :: ", -____ + (\
                ____ = __ * (__ * ___[_++] + ___[_]) + ___[++_])
} 
BEGIN { FS = RS ; CONVFMT = "%.250g" } ($++NF = ______($!_))^_'

---

echo '
00:00:00 00:01:03 00:05:57 00:08:27 00:11:58 00:14:50
00:20:19 00:25:06 00:33:17 00:38:21 00:42:30 00:46:11
00:51:33 01:00:04 01:00:56 01:04:15 01:09:13 01:16:51
                                    01:20:03 01:27:58'

---

 duration :: 63
 duration :: 294
 duration :: 150
 duration :: 211
 duration :: 172

 duration :: 329
 duration :: 287
 duration :: 491
 duration :: 304
 duration :: 249

 duration :: 221
 duration :: 322
 duration :: 511
 duration :: 52
 duration :: 199

 duration :: 298
 duration :: 458
 duration :: 192
 duration :: 475

---

事实上，您甚至可以直接读出HH、MM、SS的原始值，按照适当的顺序，因为

  ____ = __ * (__ * ___[_++] + ___[_]) + ___[++_] 
    ⬇                                           
  chap = 60 * (60 *     HH   +    MM ) +     SS