INTEGER1 -le INTEGER2—— 如果 INTEGER1 等于或小于 INTEGER2,则为真。 h FILE—— 如果 FILE 存在并且是符号链接,则为真。 r FILE—— 如果 FILE 存在并且可读,则为真。 w FILE—— 如果 FILE 存在且可写,则为真。 x FILE—— 如果 FILE 存在且可执行,则为真。 d FILE—— 如果 FILE 存在并且...
# 写法一iftest-e /tmp/foo.txt ;thenecho"Found foo.txt"fi# 写法二if[ -e /tmp/foo.txt ] ;thenecho"Found foo.txt"fi# 写法三if[[ -e /tmp/foo.txt ]] ;thenecho"Found foo.txt"fi 判断表达式 if关键字后面,跟的是一个命令。这个命令可以是test命令,也可以是其他命令。命令的返回值为0表示...
valint() #@ USAGE: valint INTEGER case ${1#-} in ## Leading hyphen removed to accept negative numbers *[!0-9]*) false;; ## the string contains a non-digit character *) true ;; ## the whole number, and nothing but the number esac 如果函数体用括号括起来,那么它是在子 shell ...
[ integer1 -gt integer2 ]:如果integer1大于integer2,则为true。 下面是一个用法的例子。 #!/bin/bashINT=-5if[ -z"$INT"];thenecho"INT is empty.">&2exit1fiif[$INT-eq 0 ];thenecho"INT is zero."elseif[$INT-lt 0 ];thenecho"INT is negative."elseecho"INT is positive."fiif[ $((...
Since that command does not exist, it creates a specific kind of error which is indicated by the program’sexit status. The exit status of a program is an integer which indicates whether the program was executed successfully or if an error occurred. The exit status of the last program run...
function check(){ local a="$1" printf "%d" "$a" &>/dev/null && echo "integer" && return printf "%d" "$(echo $a|sed 's/^[+-]\?0\+//')" &>/dev/null && echo "integer" && return printf "%f" "$a" &>/dev/null && echo "number" && return ...
‘test’: Check file types and compare values man test(获取帮助) test的判断表达式分为4类 string integer expression file testexits with the status determined by EXPRESSION. Placing the EXPRESSION between square brackets ([and]) is the same as testing the EXPRESSION withtest. ...
The proper way to handle errors is to check if the program finished successfully or not, using return codes. It sounds obvious but return codes, an integer number stored in bash$?or$!variable, have sometimes a broader meaning. Thebash man pagetells you: ...
#Check the input number [ $#-lt3] && {echo-e"Invalid input.\nUsage $(basename $0) Number1 Number2 Number3"; exit1; } #Get the input number and checkifit is a integer declare-a arrayforiin`seq02`;doif[[ $1=~ ^[0-9]+$ ]];thenarray[$i]=$1shiftelsearray[$i]=0echo-e"...
echo "Result as rounded integer:" echo $userinput | bc 1. 2. 3. 4. 5. 6. 7. 8. 9. 18. Redirections 18.1. STDOUT from bash script to STDERR #!/bin/bash echo "Redirect this STDOUT to STDERR" 1>&2 To prove that STDOUT is redirected to STDERR we can redirect script's output...