Linux if then else allows you to build a branch in a script and create conditional logic (so it is not technically a command, but a keyword).Purpose - Learn what if is for and how to find help. Options - Review a few common options and arguments. Examples - Walk through code ...
if 条件测试操作 then 命令序列1 else 命令序列2 fi c、多分支结构: 代码语言:javascript 复制 if 条件测试擦做1 then 命令序列1 elif 条件测试操作2 then 命令序列2 else 命令序列3 fi 3、实战演示: 判断文件是否存在,不存在的话,就创建一个这样的文件: 代码语言:javascript 复制 #!/bin/bash if [ ...
# Check presence of AT command if ! which at >/dev/null; then echo "remind: AT utility is required but not installed on your system. Install it with your package manager of choice, for example 'sudo apt install at'." return fi # Run commands: list, clear if [[ $COUNT -eq 1...
else max_low_pfn = max_pfn; high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1; #endif ... } <kernel/arch/x86/kernel/e820.c> /* * All of RAM fits into lowmem - but if user wants highmem * artificially via the highmem=x boot parameter then create * it: */ stat...
In this section, we'll see couple of examples of the 'if/elif/else' statement.Exampe #1:#!/bin/bash # b.sh if [ "$#" -gt 0 ] then echo "There are $# args!" fi if [ "$1" = "arg1" ] then echo "argument 1 is $1" fi Output:...
If a native build is happening, # then ARCH is assigned, getting whatever value it gets normally, and # SUBARCH is subsequently ignored. ifneq ($(CROSS_COMPILE),) SUBARCH := $(shell echo $(CROSS_COMPILE) | cut -d- -f1 | sed 's:^.*/::g') else SUBARCH := $(shell uname -m...
C shell 、Korn shell等。...常用的环境变量HOME 保存用户目录PATH 保存用冒号分割的目录路径名TERM 终端类型(xterm图形终端 linux文本终端)UID 当前用户的标识符 取值是由数字构成的字符串PWD 当前工作目录的绝对路径名...常用shell语句 if语句 if then elif then else fi test 测试命令 test expression 或 [...
id=<your_azure_subscription_id> my_resource_group=<your_azure_resource_group_name_containing_your_azure_linux_vm> my_linux_vmss=<your_azure_linux_vmss_name> my_diagnostic_storage_account=<your_azure_storage_account_for_storing_vm_diagnostic_data> # Login to Azure before you do anything else...
udevd names the links by interface type, and then by manufacturer and model information, serial number, and partition (if applicable). udevd根据接口类型、制造商和型号信息、序列号以及分区(如果适用)来命名链接。 But how does udevd know which symbolic links to create, and how does it create them...
\2. IMG_FILE 指镜像文件。 \3. 若从镜像文件写回 device 时,device 容量需与相当。 \4. 通常用制作开机磁片。 Linux 命令大全 (2) Linux-chattr命令 Linux chattr命令 Linux 命令大全 Linux chattr命令用于改变文件属性。 这项指令可改变存放在ext2文件系统上的文件或目录属性,这些属性共有以下8种模式: ...