/bin/bashif[$#-ne 1 ];thenecho"Error: Invalid number of arguments"exit1fifile=$1if[ -f$file];thenecho"$fileis a regular file."elif[ -L$file];thenecho"$fileis a soft link."elif[ -d$file];thenecho"$fileis a directory."elseecho"$filedoes not exist"fi 在脚本的开始,我们检查一...
if [[ str > xyz ]];then 5、使用内置命令:test 判断式 if test "str" \> "xyz";then 6、使用内置命令:[判断式] 类似test if [ "str" \> "xyz" ];then 7、使用-a -o进行逻辑组合 [ -r filename -a -x filename ] 8、命令&&命令 if grep -q "rm" fn.sh && [ $a -lt 100 ];t...
/bin/bash # Calculate the week number using the date command: WEEKOFFSET=$[ $(date +"%V") % 2 ] # Test if we have a remainder. If not, this is an even week so send a message. # Else, do nothing. if [ $WEEKOFFSET -eq "0" ]; then echo "Sunday evening, put out the gar...
if test -z "$age" then #Print the error message for empty echo "The input value is empty." exit fi #Check whether the input value is a number or not if ! [[ $age =~ ^[0-9]+$ ]]; then #Print the error message for non-numeric data echo "The age value must be a numbe...
string="test string" echo "${#string}" # output: 11 str1="test_str1" str2="test_str2" str3=$str1$str2 echo "$str3" # output: test_str1test_str2 # 通过 {} 提高可读性 str4="${str1}_yes" echo "$str4" # output: test_str1_yes pos=5 len=4 echo "${str4:$pos:$le...
Exits with a status of 0 (true) or 1 (false) depending on the evaluation of EXPR. The behavior of test depends on the number of arguments. Read the bash manual page for the complete specification. String operators: -z STRING True if string is empty. ...
if[[$USER_INPUT=="hello"]];then echo"Hello to you as well" fi In this example above we use the basicIFcondition with a single test of string equality and then print some output in case the condition is true based on input from the user. Note, you can place theTHENstatement on the...
1. Bash If..then..fi statement if [ conditional expression ] then statement1 statement2 . fi This if statement is also called as simple if statement. If the given conditional expression is true, it enters and executes the statements enclosed between the keywords “then” and “fi”. If th...
在Bash/Shell脚本中,可以使用特殊字符"\n"来表示换行符。当需要在变量中插入换行符时,可以使用以下方法: 1. 使用双引号(")包裹字符串,并在需要插入换行符的位置使用"\n"。例如: `...
查看man bash 里面对test命令不同参数个数的判断结果说明如下: test and [ evaluate conditional expressions using a set of rules based on the number of arguments. 0 arguments The expression is false. 1 argument The expression is true if and only if the argument is not null. ...