bash shell command-line 答案除了反引号( `command` )之外,你可以使用$(command) ,我发现它更容易阅读,并允许嵌套。 OUTPUT="$(ls -1)" echo "${OUTPUT}" MULTILINE=$(ls \ -1) echo "${MULTILINE}" 引用( " )对保留多行值很重要。 更新(2018 年):正确的方法是 $(sudo run command) 你使用...
variable_name=$(command \argument 1 \argument 2 \argument 3) 下面的 bash 指令碼演示了將多行命令的輸出分配給變數。ls命令列出當前資料夾的所有內容,並將輸出通過管道傳送到head命令。head命令僅從ls中選擇輸入的前5行並將輸出通過管道傳輸到grep命令。grep命令匹配帶有單詞flow的行並將其列印到標準輸出。
You can store the output of command substitution into any loop variable which is shown in the next example. Example#5: Create a file namedcmdsub2.shwith the following code. Here, `ls -d */` command is used to retrieve all directory list from the current directory. For loop is used he...
$ unset x $ showvar $x is not set $ x=3 $ showvar $x is not set $ export x $ showvar $x = 3 $ x= ## in bash, reassignment doesn't remove a variable from the environment $ showvar $x is set but empty 注意 showvar不是一个 bash 命令,而是一个如清单 5-1 所示的脚本,...
command, not just those that precede thecommandname.-mJob control is enabled.-nRead commands butdonot execute them.-ooption-name Set the variable corresponding to option-name: allexport same as-abraceexpand same as-Bemacs use an emacs-style line editing interface ...
tion,declareandtypeset makeeachname local,aswiththe local command, unless the -goptionissup‐ plied.Ifa variable nameisfollowedby=value, the valueofthe variableissettovalue.Whenus‐ ing -aor-Aandthe compound assignment syntaxtocreate array variables, additional attributesdonottakeeffectuntilsubsequent...
# "VARIABLE =value"# ^#% Script tries to run "VARIABLE" command with one argument, "=value".# "VARIABLE= value"# ^#% Script tries to run "value" command with#+ the environmental variable "VARIABLE" set to "".#---## 变量引用echohello# hello# Not a variable reference, just the s...
$ bash set1.bash Read the values of the variable using the “echo” command: $ echo $v1 $v2 $v3 The following output appears after executing the previous commands: Example 2: Using the Set Command with -C Option Run the “cat” command to create a text file namedtestfile.txt. Next...
You can assign data to a variable using the equals sign (=). The data you store in a variable can either be a string or a number. Let’s create a variable now on the command line: chapter_number=5 The variable name is on the left hand side of the equals sign, and the data whic...
regex`trap'exit 42'sigint# Unportable signal speccmd &> file# Unportable redirection operatorreadfoo < /dev/tcp/host/22# Unportable intercepted filesfoo-bar() { ..; }# Undefined/unsupported function name[$UID= 0 ]# Variable undefined in dash/shlocalvar=value# local is undefined in shtim...