如何将代码添加到.bashrc而不引起错误？

Question

我正在学习如何将我的 NIC 传递到我的 KVM。

本指南说将以下代码添加到文件 ~/.bashrc

#!/bin/bash
# change the 999 if needed
shopt -s nullglob
for d in /sys/kernel/iommu_groups/{0..999}/devices/*; do
    n=${d#*/iommu_groups/*}; n=${n%%/*}
    printf 'IOMMU Group %s ' "$n"
    lspci -nns "${d##*/}"
done;

我不清楚代码应该插入哪里，所以它在第1-8行。

  1 #!/bin/bash
  2 # change the 999 if needed
  3 shopt -s nullglob
  4 for d in /sys/kernel/iommu_groups/{0..999}/devices/*; do
  5         n=${d#*/iommu_groups/*}; n=${n%%/*}
  6         printf 'IOMMU Group %s ' "$n"
  7         lspci -nns "${d##*/}"
  8 done;
  9 
 10 # ~/.bashrc: executed by bash(1) for non-login shells.
 11 # see /usr/share/doc/bash/examples/startup-files (in the package bash-doc)
 12 # for examples
 13 
 14 # If not running interactively, don't do anything
 15 case $- in
 16     *i*) ;;
 17       *) return;;
 18 esac
 19 
 20 # don't put duplicate lines or lines starting with space in the history.
 21 # See bash(1) for more options
 22 HISTCONTROL=ignoreboth
 23 
 24 # append to the history file, don't overwrite it
 25 shopt -s histappend
 26 
 27 # for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
 28 HISTSIZE=1000
 29 HISTFILESIZE=2000
 30 
 31 # check the window size after each command and, if necessary,
 32 # update the values of LINES and COLUMNS.
 33 shopt -s checkwinsize
 34 
 35 # If set, the pattern "**" used in a pathname expansion context will
 36 # match all files and zero or more directories and subdirectories.
 37 #shopt -s globstar
 38 
 39 # make less more friendly for non-text input files, see lesspipe(1)
 40 [ -x /usr/bin/lesspipe ] && eval "$(SHELL=/bin/sh lesspipe)"
 41 
 42 # set variable identifying the chroot you work in (used in the prompt below)
 43 if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
 44     debian_chroot=$(cat /etc/debian_chroot)
 45 fi
 46 
 47 # set a fancy prompt (non-color, unless we know we "want" color)
 48 case "$TERM" in
 49     xterm-color|*-256color) color_prompt=yes;;
 50 esac
 51 
 52 # uncomment for a colored prompt, if the terminal has the capability; turned
 53 # off by default to not distract the user: the focus in a terminal window
 54 # should be on the output of commands, not on the prompt
 55 #force_color_prompt=yes
 56 
 57 if [ -n "$force_color_prompt" ]; then
 58     if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
 59         # We have color support; assume it's compliant with Ecma-48
 60         # (ISO/IEC-6429). (Lack of such support is extremely rare, and such
 61         # a case would tend to support setf rather than setaf.)
 62         color_prompt=yes
 63     else
 64         color_prompt=
 65     fi
 66 fi
 67 
 68 if [ "$color_prompt" = yes ]; then
 69     PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$     '
 70 else
 71     PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
 72 fi
 73 unset color_prompt force_color_prompt
 74 
 75 # If this is an xterm set the title to user@host:dir
 76 case "$TERM" in
 77 xterm*|rxvt*)
 78     PS1="\[\e]0;${debian_chroot:+($debian_chroot)}\u@\h: \w\a\]$PS1"
 79     ;;
 80 *)
 81     ;;
 82 esac
 83 
 84 # enable color support of ls and also add handy aliases
 85 if [ -x /usr/bin/dircolors ]; then
 86     test -r ~/.dircolors && eval "$(dircolors -b ~/.dircolors)" || eval "$(dircolors -b)"
 87     alias ls='ls --color=auto'
 88     #alias dir='dir --color=auto'
 89     #alias vdir='vdir --color=auto'
 90 
 91     alias grep='grep --color=auto'
 92     alias fgrep='fgrep --color=auto'
 93     alias egrep='egrep --color=auto'
 94 fi
 95 
 96 # colored GCC warnings and errors
 97 #export GCC_COLORS='error=01;31:warning=01;35:note=01;36:caret=01;32:locus=01:quote=01'
 98 
 99 # some more ls aliases
100 alias ll='ls -alF'
101 alias la='ls -A'
102 alias l='ls -CF'
103 
104 # Add an "alert" alias for long running commands.  Use like so:
105 #   sleep 10; alert
106 alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1    |sed -e '\''s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'
107 
108 # Alias definitions.
109 # You may want to put all your additions into a separate file like
110 # ~/.bash_aliases, instead of adding them here directly.
111 # See /usr/share/doc/bash-doc/examples in the bash-doc package.
112 
113 if [ -f ~/.bash_aliases ]; then
114     . ~/.bash_aliases
115 fi
116 
117 # enable programmable completion features (you don't need to enable
118 # this, if it's already enabled in /etc/bash.bashrc and /etc/profile
119 # sources /etc/bash.bashrc).
120 if ! shopt -oq posix; then
121   if [ -f /usr/share/bash-completion/bash_completion ]; then
122     . /usr/share/bash-completion/bash_completion
123   elif [ -f /etc/bash_completion ]; then
124     . /etc/bash_completion
125   fi
126 fi

但是，当使用命令 ./.bashrc 运行 .bashrc 时，这会导致错误

ubuntu@ubuntu:~$ ./.bashrc 
./.bashrc: line 17: return: can only `return' from a function or sourced script

Answer 1

您遵循的指南不会告诉您将此代码添加到~/.bashrc，而是告诉您将其作为脚本运行。该页面中没有提及~/.bashrc任何地方。这是有道理的。~/.bashrc每次启动新的交互式非登录 shell 会话时，都会执行 中的任何命令。所以每次你打开终端时。您不想每次都运行此代码！

没有必要，代码不是为此设计的，请注意它将如何为找到的每个文件打印一条消息。

最后，代码本身被编写为脚本，以#!/bin/bash shebang 行开头，进一步表明它与 in 无关~/.bashrc，并且在任何情况下，该代码除了打印出信息之外不执行任何操作：

• shopt -s nullglob：打开nullglob 选项。
• for d in /sys/kernel/iommu_groups/{0..999}/devices/*; do：迭代 中的所有文件/sys/kernel/iommu_groups/{0..999}/devices/，即/sys/kernel/iommu_groups/名称为 0 到 999 之间的数字的所有目录，然后是devices其下所有子目录中的所有文件。
• n=${d#*/iommu_groups/*}; n=${n%%/*}：使用shell 字符串操作来提取 IOMMU 组的名称、当前子目录的名称/sys/kernel/iommu_groups/（这是一种奇怪而复杂的方法，但指南建议这样做）。
• lspci -nns "${d##*/}"：使用该lspci命令打印出这些指向的设备的文本和数字 ID。

所以这只是一种提取信息供您查看和使用的简单方法。这里没有什么自动的，它只是将内容打印到终端。

为了完整起见，这里有一个更简单的方法来完成同样的事情，但不要将其放入您的 中~/.bashrc，只需运行一次，然后查看输出，然后按照指南进行操作。但这次请尝试更仔细地阅读指南！

$ for d in /sys/kernel/iommu_groups/[0-9]*; do 
  [ -e "$d"/devices ] && printf 'IOMMU Group %s\n' "${d##*/}" ; 
done 

在我的系统上，返回：

IOMMU Group 0
IOMMU Group 1
IOMMU Group 10
IOMMU Group 11
IOMMU Group 12
IOMMU Group 13
IOMMU Group 14
IOMMU Group 15
IOMMU Group 16
IOMMU Group 17
IOMMU Group 18
IOMMU Group 2
IOMMU Group 3
IOMMU Group 4
IOMMU Group 5
IOMMU Group 6
IOMMU Group 7
IOMMU Group 8
IOMMU Group 9