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这是我用来保存相机文件并从 0001 开始命名的代码。相机运行 Busybox，里面有一个灰壳。
该代码基于 Charles Duffy 先前的回答。

#!/bin/sh                                                                                                               
# Snapshot script                                                                                           
cd /mnt/0/foto                                                                                                          

sleep 1                                                                                                                 

set -- *.jpg            # put the sorted list of picture namefiles on argv ( the number of files on the list can be requested by echo $# )                                                           
while [ $# -gt 1 ]; do  # as long as there's more than one...                                                            
  shift                 # ...some rows are shifted until only one remains                                                          
done                                                                                                                    

if [ "$1" = "*.jpg" ]; then  # If cycle to determine if argv is empty because there is no jpg file present in the dir.         #argv is set so that following cmds can start the sequence from 0 on.                                                                              
set -- snapfull0000.jpg                                                                                                 
else                                                                                                                    
echo "Piu' di un file jpg trovato."                                                                                     
fi                                                                                                                      

num=${1#*snapfull}                     # $1 is the first row of $#. The alphabetical part of the filename is removed.                                        
num=${num%.*}                          # removes the suffix after the name.                                   
num=$(printf "%04d" "$(($num + 1))")   # the variable is updated to the next digit and the number is padded (zeroes are added)

                      # echoes for debug                                                                                 
echo "variabile num="$num              # shows the number recognized in the latest filename                                                                                     
echo "\$#="$#                          # displays num of argv variables                                                                                
echo "\$1="$1                          # displays the first arg variable                                                                                   


wget http://127.0.0.1/snapfull.php -O "snapfull${num}.jpg"  # the snapshot is requested to the camera, with the sequential naming of the jpeg file.

这是我在脚本操作期间在 cmd 行上得到的。我手动运行脚本九次，但在保存文件snapfull0008.jpg后，如您在最后几行中看到的，文件仅命名为snapfull0000.jpg。

# ./snap4.sh                                                                                                            
variable num=0001                                                                                                      
$#=1                                                                                                                    
$1=snapfull0000.jpg                                                                                                     
Connecting to 127.0.0.1 (127.0.0.1:80)                                                                                  
127.0.0.1 127.0.0.1 - [05/Dec/2014:20:22:22 +0000] "GET /snapfull.php HTTP/1.1" 302 0 "-" "Wget"                        
snapfull0001.jpg     100% |*******************************|   246k --:--:-- ETA                                         
# ./snap4.sh                                                                                                            
More than a jpg file found.                                                                                            
variable num=0002                                                                                                      
$#=1                                                                                                                    
$1=snapfull0001.jpg                                                                                                     
Connecting to 127.0.0.1 (127.0.0.1:80)                                                                                  
127.0.0.1 127.0.0.1 - [05/Dec/2014:20:22:32 +0000] "GET /snapfull.php HTTP/1.1" 302 0 "-" "Wget"                        
snapfull0002.jpg     100% |*******************************|   249k --:--:-- ETA                                         
# ./snap4.sh                                                                                                            
More than a jpg file found.                                                                                            
variable num=0003                                                                                                      
$#=1                                                                                                                    
$1=snapfull0002.jpg                                                                                                     
Connecting to 127.0.0.1 (127.0.0.1:80)                                                                                  
127.0.0.1 127.0.0.1 - [05/Dec/2014:20:22:38 +0000] "GET /snapfull.php HTTP/1.1" 302 0 "-" "Wget"                        
snapfull0003.jpg     100% |*******************************|   248k --:--:-- ETA                                         
# ./snap4.sh                                                                                                            
More than a jpg file found.                                                                                            
variable num=0004                                                                                                      
$#=1                                                                                                                    
$1=snapfull0003.jpg                                                                                                     
Connecting to 127.0.0.1 (127.0.0.1:80)                                                                                  
127.0.0.1 127.0.0.1 - [05/Dec/2014:20:22:43 +0000] "GET /snapfull.php HTTP/1.1" 302 0 "-" "Wget"                        
snapfull0004.jpg     100% |*******************************|   330k --:--:-- ETA                                         
# ./snap4.sh                                                                                                            
More than a jpg file found.                                                                                            
variable num=0005
$#=1                                                                                                                    
$1=snapfull0004.jpg                                                                                                     
Connecting to 127.0.0.1 (127.0.0.1:80)                                                                                  
127.0.0.1 127.0.0.1 - [05/Dec/2014:20:22:51 +0000] "GET /snapfull.php HTTP/1.1" 302 0 "-" "Wget"                        
snapfull0005.jpg     100% |*******************************|   308k --:--:-- ETA                                         
# ./snap4.sh                                                                                                            
More than a jpg file found.                                                                                            
variable num=0006                                                                                                      
$#=1                                                                                                                    
$1=snapfull0005.jpg                                                                                                     
Connecting to 127.0.0.1 (127.0.0.1:80)                                                                                  
127.0.0.1 127.0.0.1 - [05/Dec/2014:20:22:55 +0000] "GET /snapfull.php HTTP/1.1" 302 0 "-" "Wget"                        
snapfull0006.jpg     100% |*******************************|   315k --:--:-- ETA                                         
# ./snap4.sh                                                                                                            
More than a jpg file found.                                                                                            
variable num=0007                                                                                                      
$#=1                                                                                                                    
$1=snapfull0006.jpg                                                                                                     
Connecting to 127.0.0.1 (127.0.0.1:80)                                                                                  
127.0.0.1 127.0.0.1 - [05/Dec/2014:20:22:59 +0000] "GET /snapfull.php HTTP/1.1" 302 0 "-" "Wget"                        
snapfull0007.jpg     100% |*******************************|   316k --:--:-- ETA                                         
# ./snap4.sh                                                                                                            
More than a jpg file found.                                                                                            
variable num=0008                                                                                                      
$#=1                                                                                                                    
$1=snapfull0007.jpg                                                                                                     
Connecting to 127.0.0.1 (127.0.0.1:80)                                                                                  
127.0.0.1 127.0.0.1 - [05/Dec/2014:20:23:04 +0000] "GET /snapfull.php HTTP/1.1" 302 0 "-" "Wget"                        
snapfull0008.jpg     100% |*******************************|   317k --:--:-- ETA                                         
# ./snap4.sh                                                                                                            
More than a jpg file found.                                                                                            
variable num=0000                                                                                                      
$#=1                                                                                                                    
$1=snapfull0008.jpg                                                                                                     
Connecting to 127.0.0.1 (127.0.0.1:80)                                                                                  
127.0.0.1 127.0.0.1 - [05/Dec/2014:20:23:10 +0000] "GET /snapfull.php HTTP/1.1" 302 0 "-" "Wget"                        
snapfull0000.jpg     100% |*******************************|   318k --:--:-- ETA

文件编号 8 后序列停止的原因可能是什么？

4

1 回答 1

6

问题是前导0s 导致数字被读取为八进制。

在 bash 中，使用$((10#$num))将强制使用小数。因此：

num=$(printf "%04d" "$((10#$num + 1))")

要使用busybox ash，您需要剥离0s。即使在busybox ash中也可以使用的一种方法：

while [ "${num:0:1}" = 0 ]; do
  num=${num:1}
done
num=$(printf '%04d' "$((num + 1))")

请参阅以下显示使用的成绩单（使用busybox v1.22.1的灰测试）：

$ num=0008
$ while [ "${num:0:1}" = 0 ]; do
>   num=${num:1}
> done
$ num=$(printf '%04d' "$((num + 1))")
$ echo "$num"
0009

如果您的 shell 甚至不支持 POSIX 所需的基本参数扩展集，您可以改为使用：

num=$(echo "$num" | sed -e 's/^0*//')
num=$(printf '%04d' "$(($num + 1))")

...虽然这意味着你的busybox是用灰以外的外壳建造的，但我强烈建议重新考虑这个决定。

于 2014-12-05T20:57:46.717 回答