although the end result is the same (see below).# ---# It is permissible to set multiple variables on the same line,#+ if separated by white space.# Caution, this may reduce legibility, and may not be portable.var1=21var2=22var3=$V3echoecho"var...
Command-line editing is one special Bash feature that's not always available with other CLIs. Bash retains a command history, which can be accessed by pressing the up arrow key. This makes it easier to precisely rerun a command. These prior commands can also be modified at the command line...
在bash中,stdin(标准输入)是指从键盘或其他输入设备读取数据的默认输入流。重定向stdin意味着将输入流从键盘或其他设备改为来自文件或其他命令的输出。 要在bash中重定向stdin,可以使用输入重定向符号"<"。以下是一些常见的用法: 从文件中读取输入: 从文件中读取输入: 这将把文件file.txt的内容作为command命令的输入...
首先,Shell 是一个程序,提供一个与用户对话的环境。这个环境只有一个命令提示符,让用户从键盘输入命令,所以又称为命令行环境(commandline,简写为 CLI)。Shell 接收到用户输入的命令,将命令送入操作系统执行,并将结果返回给用户。本书中,除非特别指明,Shell 指的就是命令行环境。 其次,Shell 是一个命令解释器,解释...
Read one line from STDIN and assigns it to a variable. popd Removes entries from the directory stack. pushd Add a directory to the directory stack. printf Displays text in a formatted string. source Read and executes commands from a specified file in the current shell. times Displays the acc...
echo "It is line 1. It is line 2. It is line 3." We can use double quotes to have a single quote in one or multiple lines; see the following example. Use echo with Double Quotes 1 2 3 4 5 echo "It is line 1. Isn't it? It is line 2. It is line 3." Similarly, ...
Zero-address ``commands'': label Labelforb and t commands.#commentThe comment extends until the next newline (or the end of a -e script frag‐ ment). } The closing bracket of a { } block. Zero- or One- address commands = Print the current line number. ...
Notice that even with just one command line in the loop script, it prints out seven echo outputs.The next type of loop is while. The script will evaluate a condition. If the condition is true, it will keep executing the commands until the output no longer meets the defined condition.#!
Exit status 127 tells you that one of two things has happened: Either the command doesn't exist, or the command isn't in your path ($PATH). This code also appears if you attempt to execute a command that is in your current working directory. For example, the script above that you ga...
Here's an example one-line command to do that: PROFILE=/dev/null bash -c 'curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.3/install.sh | bash'Installing in DockerWhen invoking bash as a non-interactive shell, like in a Docker container, none of the regular profile ...