Bash string comparison It is advisable always to check and compare if two strings are equal in a Bash script; this is quite important for different reasons. If two strings are equal in a Bash script, it implies that both strings have the same length and character sequence. The “if” stat...
= STRIN2 # Trueifstrings arenotequal#算术测试操作var1 -eq var2 # Trueifvar1 is equal to var2var1 -ne var2 # Trueifvar1notequal to var2var1 -lt var2 # Trueifvar1 is less than var2var1 -le var2 # Trueifvar1 is less thanorequal ...
[ STRING1 > STRING2 ] 如果 “STRING1” sorts after “STRING2” lexicographically in the current locale则为真。 [ ARG1 OP ARG2 ] “OP” is one of -eq, -ne, -lt, -le, -gt or -ge. These arithmetic binary operators return true if “ARG1” is equal to, not equal to, less than,...
In this example, we have two variables, ‘a’ and ‘b’. The script checks if ‘a’ is equal to ‘b’. If it’s not, it moves on to the ‘elif’ statement to check if ‘a’ is greater than ‘b’. If neither condition is met, it executes the ‘else’ statement, which in t...
如果if结构使用的不是test命令,而是普通命令,比如上一节的((...))算术运算,或者test命令与普通命令混用,那么可以使用 Bash 的命令控制操作符&&(AND)和||(OR),进行多个命令的逻辑运算。$ command1 && command2 $ command1 || command2对于&&操作符,先执行command1,只有command1执行成功后, 才会执行command2。
"which is not read as a comment. First line is also a place where you put your interpreter which is in this case: /bin/bash. Here is our first bash shell script example: #!/bin/bash # declare STRING variable STRING="Hello World" #print variable on a screen echo $STRING...
file f1 is newer than f2. f1 -ot f2 file f1 is older than f2 Comparison Operators Comparison operators are used in bash to compare two strings to check if they are equal or not. Here, we will list some comparison operators including, string, and integer operators. Integer Operators Operat...
If you’re making Bash programs for you or for others to use one way you can get user input is to specify arguments for users to provide to your program, as we discussed in the previous section. You could also ask users to type in a string on the command line by temporarily stopping...
[ STRING1 > STRING2 ] 如果 “STRING1” sorts after “STRING2” lexicographically in the current locale则为真。 [ ARG1 OP ARG2 ] “OP” is one of -eq, -ne, -lt, -le, -gt or -ge. These arithmetic binary operators return true if “ARG1” is equal to, not equal to, less than...
This is an alternative to sed, awk, perl and other tools. The function below works by finding all leading and trailing white-space and removing it from the start and end of the string. The : built-in is used in place of a temporary variable....