Y=4 empty_string="" if[ $X -lt $Y ]# is $X less than $Y ? then echo"$X=${X}, which is smaller than $Y=${Y}" fi if[ -n"$empty_string"];then echo"empty string is non_empty" fi if[ -e"${HOME}/.fvwmrc"];then# test to see if ~/.fvwmrc exists echo"you have ...
if grep -q root /etc/passwd; then echo account root exists else echo account root not exist fi [root@jfht ~]#if grep -q root /etc/passwd; then >echo account root exists >else >echo account root not exist >fi account root exists [root@jfht ~]# 示例六 判断文件是否存在 if [ -e...
echo"File exists but is empty" fi else echo"File does not exist" fi In this bash script example, we first set the filename, the size_threshold variable and then check if any file exists with the given name using the -e option. If it exists, we use the wc command to get the file...
-r FILE_NAM # True if FILE_NAM is readable -s FILE_NAM # True if FILE_NAM exists and is not empty -w FILE_NAM # True if FILE_NAM has write permission -x FILE_NAM # True if FILE_NAM is executable 字符串测试操作 -z STRING # True if STRING is empty -n STRING # True if STRI...
[[ $variable -eq|ne|gt|lt|ge|le integer ]] - Test if the specified variable has a [n]on-empty value: [[ -n $variable ]] - Test if the specified variable has an empty value: [[ -z $variable ]] - Test if the specified [f]ile exists: ...
echo "$a : The string is not empty" else echo "$a : The string is empty" fi 1. 2. 3. 4. 5. 6. 7. 8. 文件比较运算符 如下例: #!/bin/bash file="/test.sh" # 由于没有给出条件,所以返回true if [ ! ] then echo "File exists" ...
Common Pitfalls and Errors Incorrect usage of the single bracket command [ How to solve the Binary Operator Expected Error? Why you should not use the || and && operators instead of a Bash If Statement? Detailed Examples & FAQ How to check if a variable exists or is “null”? How to ...
TestFile1doesnotexistorisempty. 1. 2. 向文件添加一些内容,然后再测试一次: 复制 [student@studentvm1 testdir]$File="TestFile1";echo"This is file $File">$File;if[-s $File];thenecho"$File exists and contains data.";elseecho"$File does not exist or is empty.";fi ...
This is also useful if the PATH variable on a system has been configured to point to an alternate version of the program. For instance, one might install a newer version of bash while preserving the original version and insert the location of the newer version into the PATH variable. The ...
Within inverted commas, we have added the variable “$F”. After this, the “then” clause started with the “echo” statement using the variable name to show if it exists or not. The “then” part of the “if-then” statement will only be executed when the condition “if” will be...