Introduction to the Bash If Statement What is the syntax of a Bash If Statement? What are the double Parentheses ((…)), single […], and double [[..]] Square Brackets? What are the Bash Conditional Expressions? How to use an If Statement with Then, Else, Else If (elif) clauses?
Using the “If -Z” Statement Sometimes, it is required to check if a string variable is empty or if it contains a string of zero length. There are many options in Bash to do this task. Using the “-z” option with the “if” statement is one of the ways to check whether a vari...
Example 3: If statement in bash on less than a number In addition to-eqfor equality you can also try-lt -le -gt -getest conditions for less than, less than or equal, greater than or greater then or equal respectively. Below is a similar example with less then operator-lt: ...
if [ ! -z err−o!−eapk ]; then 会报出-e无法找到的错误; 而if [ ! -z err]||[!−eapk ]; then 没问题; 整数比较 : -eq 等于,如:if [ "a"−eq"b" ] -ne 不等于,如:if [ "a"−ne"b" ] -gt 大于,如:if [ "a"−gt"b" ] -ge 大于等于,如:if [ "a"−ge...
chmod -options filename 1. l.gzip 压缩文件。 gzip filename 1. m.gunzip 解压缩gzip压缩的文件。 gunzip filename 1. n.gzcat 让你查看gzip压缩文件,而不需要gunzip它。 gzcat filename 1. o.lpr 打印文件。 lpr filename 1. p.lpq 查看打印机队列。
statement3 statement4 ... fi 多分支的if语句 if 判断条件1; then statement1 ... elif 判断条件2; then statement2 ... elif 判断条件3; then statement3 ... else statement4 ... fi 练习:写一个脚本 判断当前系统上是否有用户的默认shell为bash; ...
If statement in Bash We can also implementifstatements for additional functions. #!/bin/bash echo “Who is there?” read name if [ $name ] echo “Hello $name” else echo “Must’ve been my imagination” fi In the terminal: ~$bash name.sh ...
if 判断条件1 then statement1 ... elif 判断条件2 then statement2 ... elif 判断条件3 then statement3 ... ... else statement4 ... fi ·bash中测试脚本是否有语法错误的方法 格式: ->sh -n 脚本名称 但是这种方法无法测试脚本中的关键字错误,但是报错未必可靠。
Learn the syntax and use of the Bash declare statement with examples. Master variable declaration and attributes in Bash scripting.
How to find if a number is odd or even in bash? You can use a bash for loop with a nested bash if statement using a bash arithmetic expansion with the module operator. for x in {1..5}; do if (( x % 2 )); then echo "\$x=$x is an odd number" else echo "\$x=$x is...