$SECONDS變量---------腳本已經運行的秒數,腳本實例:
1 #!/bin/bash - 2 #=========================================================================================== 3 # 4 # 5 # FILE:seconds.sh 6 # USAGE:./seconds.sh 7 # DESCRIPTION: 8 # 9 # OPTIONS:--- 10 # REQUIREMENTS:--- 11 # BUGS:--- 12 # NOTES:--- 13 # AUTHOR:Yuan Shaoqian(Mark),[email protected] 14 # ORGANIZATION: 15 # CREATED:09/02/2016 21:19 16 # REVISION:--- 17 #=========================================================================================== 18 TIME_LIMIT=10 19 INTERVAL=1 20 21 echo 22 echo "Hit Control-C to exit before $TIME_LIMIT seconds." 23 echo 24 25 while [ "$SECONDS" -le "$TIME_LIMIT" ] 26 do # $SECONDS is an internal shell variable 27 if [ "$SECONDS" -eq 1 ] 28 then 29 units=second 30 else 31 units=seconds 32 fi 33 34 echo "This script has been running $SECONDS $units." 35 #On a slow or overburdened machine,the script may skip a count every once in a while. 36 sleep $INTERVAL 37 done 38 exit 0
$HOME變量-------------用於引用Bash實例的全路徑名。
$IFS變量--------IFS時內部字段分隔符的縮寫。此變量決定當Bash解析字符串時將怎樣識別字段,或單詞分界線。變量$IFS的默認值是空格(空格/制表符/換行),但可以被修改。
1 $ set x y z 2 $ IFS=“:;-” 3 $ echo "$*" 4 x:y:z
$OSTYPE變量-----操作系統的類型
$TMOUT變量------如果$TMOUT被指定了一個非零的值,此值會被Bash的內部命令read作為默認的超時秒數。
1 set -o nounset 2 TMOUT=3 3 4 echo "Are you sure?(Y/N)" 5 read input 6 7 if [ "$input" == "Y" ] 8 then 9 echo "Continue..." 10 else 11 echo "Exit!" 12 fi
$UID變量------當前用戶的賬號識別碼(ID號),與/etc/passwd中記錄的相同,$UID是一個只讀變量,不支持修改。
1 root_id=0 2 if [ "$UID" -eq "$root_id" ] 3 then 4 echo "You are root." 5 else 6 echo "You are just an ordinary user." 7 fi 8 9 exit 0
http://xxxxxx/Linuxjc/1155428.html TechArticle