成对处理文件 [英] Process files in pairs

问题描述

我有一个文件列表：

  file_name_FOO31101.txt 
 file_name_FOO31102.txt 
 file_name_FOO31103。 txt 
 file_name_FOO31104.txt 
  

我想使用一对文件输入到下游程序如：

  program_call file_name_01.txt file_name_02.txt 
 program_call file_name_03.txt file_name_04.txt 
 ... 
  

我不想：

  program_call file_name_02.txt file_name_03.txt 
  

我需要

$ p $ ＃！/ bin / bash

FILES =路径/ to / files

用于$ FILES / *。txt文件;


$ b $ stem = $（basename$ {file}）＃stem：file_name_FOO31104_info.txt
output_base = $（echo $ stem | cut -d '_'-f 1,2,3）＃output_base：FOO31104_info.txt
id = $（echo $ stem | cut -d'_'-f 3）＃获取第一个字段：FOO31104
number = $（echo -n $ id | tail -c 2）＃得到最后两位：04
$ b $ echo $ id $（（id + 1））

完成


但是这不会产生我想要的。

在每个循环中，我要调用一次程序，并输入两个文件（第一个文件的最后两个数字总是奇数 01 ，第二个文件的最后两个数字总是偶数 02 ）

解决方案

实际上我根本不会使用作为循环。 while 循环 shift s files off是完全合理的方式。

 ＃在这里，我们用文件列表
＃覆盖参数列表... ...如果你想要的话，你可以在函数中做到这一点保持全局参数列表完好
 set  - $ FILES/ *。txt ##没有这些引号路径与空格破解
 
＃处理没有找到匹配我们的文件的情况glob 
 [[-e $ 1 || -L $ 1]] || {echo$ FILES中找不到.txt>& 2;出口1; （$$＃> 1））; 
 
在这里，我们正在做自己的循环， do ##在循环中只有w / 2或更多剩余
 echo正在处理文件$ 1和$ 2## ...在这里替换你自己的逻辑... 
 shift 2 || break ##即使测试不处理这种情况，也可以打破
完成
 
＃...并为有奇数个文件的情况添加自己的处理。 
（（$＃））&&回声遗留文件$ 1仍然存在
  

请注意 $＃ / code> s在这里引用（（））在StackOverflow的语法突出显示，而不是因为他们需要。 ：）

---

顺便说一句 - 考虑使用bash的本地字符串操作。 $ b

  stem = $ {file ## * /} 
 IFS = _ read -r p1 p2 id p_rest <<< $ $
 $ number $ $ $（$ {＃id}  -  2））} 
 output_base =$ {p1} $ {p2} $ {id}
 echo$ id $ （（10＃number + 1））＃10＃确保解释为十进制，不是八进制
  

I have a list of files:

file_name_FOO31101.txt
file_name_FOO31102.txt
file_name_FOO31103.txt
file_name_FOO31104.txt

And I want to use pairs of files for input into a downstream program such as:

program_call file_name_01.txt file_name_02.txt
program_call file_name_03.txt file_name_04.txt
...

I do not want:

program_call file_name_02.txt file_name_03.txt

I need to do this in a loop as follows:

#!/bin/bash

FILES=path/to/files

for file in $FILES/*.txt;

do

    stem=$( basename "${file}" ) # stem : file_name_FOO31104_info.txt
    output_base=$( echo $stem | cut -d'_' -f 1,2,3 )  # output_base : FOO31104_info.txt
    id=$( echo $stem | cut -d'_' -f 3 ) # get the first field : FOO31104
    number=$( echo -n $id | tail -c 2 ) # get the last two digits : 04

     echo $id $((id+1))

done

But this does not produce what I want.

In each loop I want to call a program once, with two files as input (last 2 digits of first file always odd 01, last 2 digits of second file always even 02)

解决方案

I actually wouldn't use a for loop at all. A while loop that shifts files off is a perfectly reasonable way to do this.

# here, we're overriding the argument list with the list of files
# ...you can do this in a function if you want to keep the global argument list intact
set -- "$FILES"/*.txt                 ## without these quotes paths with spaces break

# handle the case where no files were found matching our glob
[[ -e $1 || -L $1 ]] || { echo "No .txt found in $FILES" >&2; exit 1; }

# here, we're doing our own loop over those arguments
while (( "$#" > 1 )); do              ## continue in the loop only w/ 2-or-more remaining
  echo "Processing files $1 and $2"   ## ...substitute your own logic here...
  shift 2 || break                    ## break even if test doesn't handle this case
done

# ...and add your own handling for the case where there's an odd number of files.
(( "$#" )) && echo "Left over file $1 still exists"

Note that the $#s are quoted inside (( )) here for StackOverflow's syntax highlighting, not because they otherwise need to be. :)

---

By the way -- consider using bash's native string manipulation.

stem=${file##*/}
IFS=_ read -r p1 p2 id p_rest <<<"$stem"
number=${id:$(( ${#id} - 2 ))}
output_base="${p1}${p2}${id}"
echo "$id $((10#number + 1))" # 10# ensures interpretation as decimal, not octal

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