Linux的基本命令格式如何Linux下经常使用的通配符有哪些
Linux的基本命令格式：
命令 [-选项] [参数]
例如
- ls -a /etc
- ls - l /etc
makdir -p /abc/cba
linux常用通配符有* ，？，[ ]，[^]，[:space:]，[:punct:]，[:lower:]，[:upper:]，[:digit:]，[:alnum:]等等。
* 匹配任意长度的任意字符
？匹配任意单个字符
[ ]匹配制定范围内的单个字符[^]匹配制定范围外的单个字符
[:space:]匹配单个空白字符
[:punct:]匹配单个标点符号字符
[:lower:]匹配单个小写字母字符
[:upper:]匹配单个大写字母字符
[:digit:]匹配单个数字字符
[:alnum:]匹配单个数字和字母字符
以上通配符在使用时还需再加一个[ ]
更多详细Linux知识可参考《Linux就该这么学》。
HG8245C cd/mnt 命令无法使用
看起来你的里面的命令是依赖busybox 的，你先确认下你的busybox 里面有没有cd 命令，好像busybox 里面是没有cd 这个命令的。
如果有的话，你打busybox cd 就可以执行了。
hyde-sun@asus:~$ busybox BusyBox v1.18.5 (Ubuntu 1:1.18.5-1ubuntu4) multi-call binary.Copyright (C) 1998-2009 Erik Andersen, Rob Landley, Denys Vlasenkoand others. Licensed under GPLv2.See source distribution for full notice.Usage: busybox [function] [arguments]... or: busybox --list[-full] or: function [arguments]... BusyBox is a multi-call binary that combines many common Unix utilities into a single executable. Most people will create a link to busybox for each function they wish to use and BusyBox will act like whatever it was invoked as.Currently defined functions: [, [[, acpid, addgroup, adduser, adjtimex, ar, arping, ash, awk, basename, blockdev, brctl, bunzip2, bzcat, bzip2, cal, cat, chgrp, chmod, chown, chroot, chvt, clear, cmp, cp, cpio, crond, crontab, cut, date, dc, dd, deallocvt, delgroup, deluser, df, diff, dirname, dmesg, dnsdomainname, dos2unix, dpkg, dpkg-deb, du, dumpkmap, dumpleases, echo, ed, egrep, eject, env, expand, expr, false, fbset, fdflush, fdisk, fgrep, find, fold, free, freeramdisk, fsck.minix, ftpget, ftpput, getopt, getty, grep, gunzip, gzip, head, hexdump, hostid, hostname,
-通配符
查询每位同学的总分和平均分（四舍五入到1位小数）的sql命令怎么写
round() ; 如下， 你直接拿去执行吧
select studentno,sum(finalscore),round(avg(finalscore),1) from score group by studentno;
round(参数,2 ) 1 就是保留一位小数， 2就是保留两位小数
-命令
