Bash脚本不会继续读取文件的下一行 [英] Bash script does not continue to read the next line of file

问题描述

我有一个Shell脚本，用于将执行命令的输出保存到CSV文件中.它从以下格式的shell脚本中读取必须执行的命令:

I have a shell script that saves the output of a command that is executed to a CSV file. It reads the command it has to execute from a shell script which is in this format:

ffmpeg -i /home/test/videos/avi/418kb.avi /home/test/videos/done/418kb.flv
ffmpeg -i /home/test/videos/avi/1253kb.avi /home/test/videos/done/1253kb.flv
ffmpeg -i /home/test/videos/avi/2093kb.avi /home/test/videos/done/2093kb.flv

您可以看到每一行都是一个ffmpeg命令.但是，该脚本仅执行第一行.就在一分钟之前，它正在执行几乎所有命令.由于某种原因，它丢失了一半.我编辑了包含命令的文本文件，现在只执行第一行.这是我的bash脚本:

You can see each line is an ffmpeg command. However, the script just executes the first line. Just a minute ago it was doing nearly all of the commands. It was missing half for some reason. I edited the text file that contained the commands and now it will only do the first line. Here is my bash script:

#!/bin/bash
# Shell script utility to read a file line line.
# Once line is read it will run processLine() function

#Function processLine
processLine(){
line="$@"

START=$(date +%s.%N)

eval $line > /dev/null 2>&1 

END=$(date +%s.%N)
DIFF=$(echo "$END - $START" | bc)

echo "$line, $START, $END, $DIFF" >> file.csv 2>&1
echo "It took $DIFF seconds"
echo $line
}

# Store file name
FILE=""

# get file name as command line argument
# Else read it from standard input device
if [ "$1" == "" ]; then
   FILE="/dev/stdin"
else
   FILE="$1"
   # make sure file exist and readable
   if [ ! -f $FILE ]; then
    echo "$FILE : does not exists"
    exit 1
   elif [ ! -r $FILE ]; then
    echo "$FILE: can not read"
    exit 2
   fi
fi
# read $FILE using the file descriptors

# Set loop separator to end of line
BAKIFS=$IFS
IFS=$(echo -en "\n\b")
exec 3<&0
exec 0<$FILE
while read line
do
    # use $line variable to process line in processLine() function
    processLine $line
done
exec 0<&3

# restore $IFS which was used to determine what the field separators are
BAKIFS=$ORIGIFS
exit 0

谢谢您的帮助.

它是ffmpeg命令，而不是无效的shell脚本.但是我应该像保罗指出的那样只使用"\ b".我还利用了约翰尼斯的短剧本.

Its the ffmpeg commands rather than the shell script that isn't working. But I should of been using just "\b" as Paul pointed out. I am also making use of Johannes's shorter script.

推荐答案

我认为应该这样做，而且似乎是正确的:

I think that should do the same and seems to be correct:

#!/bin/bash

CSVFILE=/tmp/file.csv

cat "$@" | while read line; do
    echo "Executing '$line'"
    START=$(date +%s)
    eval $line &> /dev/null
    END=$(date +%s)
    let DIFF=$END-$START

    echo "$line, $START, $END, $DIFF" >> "$CSVFILE"
    echo "It took ${DIFF}s"
done

不?

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