bash实现目录中的变量

Question

I have a serial number: SX410-251509-0171

In my code I extract the 2 digit year (15 in example above) and the 2 digit week (09 in the example above) and want to use these in a file directory.

#! /bin/bash           

year=${serial:8:2}
week=${serial:10:2}
dir="/home/jbon/20$year/$week/$serial/run0/output_log"
echo $dir    

When I run this code I'm getting the following output:

/run0/output_log015/09/SX410-251509-0171

I'm guessing the issue is around how I am using the variables in the string.

Answer 1

It sounds like you are running the script with sh , not bash , and your sh links to a shell other than bash that doesn't recognize the substring expansion operator. However, you can rewrite it in a POSIX-compliant fashion:

yearweek=${serial##*AB}   # Drop everything up to and including AB
yearweek=${yearweek%%-*}  # Drop everything from - onward
year=${yearweek%??}       # Drop the two-digit week
week=${yearweek#??}       # Drop the two-digit year