shell文件存在的判断 shell数组

以你之姓@ 2022-08-06 14:11 185阅读 0赞

判断文件：  
  
    WORKDIR=/home/tmp  
    LOCAL\_LIST\_FILE=$WORKDIR/local.list  
  
    \#if no local.txt file, generate a new one  
    if \[ ! -f  "$LOCAL\_LIST\_FILE" \]; then  
      touch $LOCAL\_LIST\_FILE  
    fi  
  
    注意：一定要有空格，判断文件是否存在，如果不存在，就生成一个新的  
  
    if \[ ! -d /mnt \]        \# be sure the directory /mnt exists  
       then  
           mkdir /mnt  
    fi  
     
    目录。/mnt是否存在，不存在就生成目录/mnt  
  
  
The tests below are test conditions provided by the shell:  
  
    \* -b file = True if the file exists and is block special file.  
    \* -c file = True if the file exists and is character special file.  
    \* -d file = True if the file exists and is a directory.  
    \* -e file = True if the file exists.  
    \* -f file = True if the file exists and is a regular file  
    \* -g file = True if the file exists and the set-group-id bit is set.  
    \* -k file = True if the files' "sticky" bit is set.  
    \* -L file = True if the file exists and is a symbolic link.  
    \* -p file = True if the file exists and is a named pipe.  
    \* -r file = True if the file exists and is readable.  
    \* -s file = True if the file exists and its size is greater than zero.  
    \* -s file = True if the file exists and is a socket.  
    \* -t fd = True if the file descriptor is opened on a terminal.  
    \* -u file = True if the file exists and its set-user-id bit is set.  
    \* -w file = True if the file exists and is writable.  
    \* -x file = True if the file exists and is executable.  
    \* -O file = True if the file exists and is owned by the effective user id.  
    \* -G file = True if the file exists and is owned by the effective group id.  
    \* file1 –nt file2 = True if file1 is newer, by modification date, than file2.  
    \* file1 ot file2 = True if file1 is older than file2.  
    \* file1 ef file2 = True if file1 and file2 have the same device and inode numbers.  
    \* -z string = True if the length of the string is 0.  
    \* -n string = True if the length of the string is non-zero.  
    \* string1 = string2 = True if the strings are equal.  
    \* string1 != string2 = True if the strings are not equal.  
    \* !expr = True if the expr evaluates to false.  
    \* expr1 –a expr2 = True if both expr1 and expr2 are true.  
    \* expr1 –o expr2 = True is either expr1 or expr2 is true.  
  
Shell中的数据问题  
  
   ArrayName=("element 1" "element 2" "element 3")  \#数组定义  
   echo $\{\#ArrayName\[@\]\}

echo "The number of elements in the array is $\{\#ArrayName\[\*\]\}"      
     
    例子  
    \#!/bin/bash  
    \# define array  
    \# name server names FQDN  
    NAMESERVERS=("ns1.nixcraft.net." "ns2.nixcraft.net." "ns3.nixcraft.net.")  
   
    \# get length of an array  
     tLen=$\{\#NAMESERVERS\[@\]\}  
   
    \# use for loop read all nameservers  
    for (( i=0; i<$\{tLen\}; i++ ));  
    do  
      echo $\{NAMESERVERS\[$i\]\}  
    done  
  
   Sample output:  
  
     ns1.nixcraft.net.  
     ns2.nixcraft.net.  
     ns3.nixcraft.net.