Question

我正在学习bash。我遇到了一些问题。 “file”看起来不像变量，看起来像一个命令只是无法理解[]中的事情任何帮助将不胜感激原始代码在这里。一些bash脚本

#!/bin/bash

# sysinfo_page - A script to produce a system information HTML file

##### Constants

TITLE="System Information for $HOSTNAME"
RIGHT_NOW=$(date +"%x %r %Z")
TIME_STAMP="Updated on $RIGHT_NOW by $USER"

##### Functions

system_info()
{
    echo "<h2>System release info</h2>"
    echo "<p>Function not yet implemented</p>"

}   # end of system_info


show_uptime()
{
    echo "<h2>System uptime</h2>"
    echo "<pre>"
    uptime
    echo "</pre>"

}   # end of show_uptime


drive_space()
{
    echo "<h2>Filesystem space</h2>"
    echo "<pre>"
    df
    echo "</pre>"

}   # end of drive_space


home_space()
{
    # Only the superuser can get this information

    if [ "$(id -u)" = "0" ]; then
        echo "<h2>Home directory space by user</h2>"
        echo "<pre>"
        echo "Bytes Directory"
        du -s /home/* | sort -nr
        echo "</pre>"
    fi

}   # end of home_space


write_page()
{
    cat <<- _EOF_
    <html>
        <head>
        <title>$TITLE</title>
        </head>
        <body>
        <h1>$TITLE</h1>
        <p>$TIME_STAMP</p>
        $(system_info)
        $(show_uptime)
        $(drive_space)
        $(home_space)
        </body>
    </html>
_EOF_

}

usage()
{
    echo "usage: sysinfo_page [[[-f file ] [-i]] | [-h]]"
}


##### Main

interactive=
filename=~/sysinfo_page.html

while [ "$1" != "" ]; do
    case $1 in
        -f | --file )           shift
                                filename=$1
                                ;;
        -i | --interactive )    interactive=1
                                ;;
        -h | --help )           usage
                                exit
                                ;;
        * )                     usage
                                exit 1
    esac
    shift
done


# Test code to verify command line processing

if [ "$interactive" = "1" ]; then
    echo "interactive is on"
else
    echo "interactive is off"
fi
echo "output file = $filename"


# Write page (comment out until testing is complete)

# write_page > $filename

Answer 1

[...]表示“可选”。 |表示“替代”。

所以[[[-f file ] [-i]] | [-h]]分解为：

[
  [
    [-f file ]
    [-i]
  ]
  |
  [-h]
]

所有参数都是可选的。如果您传递参数，则可以传递[-f file] [-i] OR [-h]。

之一

这种约定的使用有点令人困惑，因为一组[]用于分组和可选标记一样多。然后，内部可选标记有点不合适，但仍然是必要的，因为单个参数仍然是可选的。

echo“usage：sysinfo_page [[[-f file] [-i]] | [-h]]”的含义

1 个答案: