因此,在上述任何一种模式下,只要有count字节,read()就会返回,即使VMIN设置为更高的数字或指定的时间VTIME尚未到期。 6、波特率 串行端口波特率设置是通过调用函数cfsetispeed()以及cfsetospeed()来设置输入输出速率,或者也可以使用cfsetspeed(),同时设置输入和输出速度。 // Set in/out baud rate to be 9600 ...
字节(bytes)定位, 对应选项 -b 字符(characters)定位,对应选项 -c 域(fileds),对应选项 -f 以字节定位 当我们执行新建一个txt文件,命令为 who.txt 其内容如下 superStar console May 27 11:05 superStar ttys000 Jun 9 18:41 superStar ttys012 May 27 11:07 cat who.txt 会输出以下类似的内容: ➜ ...
string as a group separator --color[=WHEN], --colour[=WHEN] use markers to highlight the matching strings; WHEN is 'always', 'never', or 'auto' -U, --binary do not strip CR characters at EOL (MSDOS/Windows) -u, --unix-byte-offsets report offsets as if CRs were not there (...
替换:-e是编辑命令,用于sed执行多个编辑任务的情况下。在下一行开始编辑前,所有的编辑动作将应用到模式缓冲区中的行上。 sed-e'1,10d'-e's/My/Your/g'datafile #选项-e用于进行多重编辑。第一重编辑删除第1-3行。第二重编辑将出现的所有My替换为Your。因为是逐行进行这两项编辑(即这两个命令都在模式空间...
-N Print non-printable characters as is. -Q Quote filenames with double quotes. -p Print the protections for each file. -u Displays file owner or UID number. -g Displays file group owner or GID number. -s Print the size in bytes of each file. ...
Alternatively, if the list of words in thedata.txtfile is separated by white space, we can match a string with six characters using this command: $ awk -v n=6'{for (i=1; i<=NF; i++) if (length($i) == n) print $i}'data.txt banana cârrot @nswer letter éééééé ...
To include a literal ] place it first in the list. Similarly, to include a literal ^ place it anywhere but first. Finally, to include a literal - place it last. Anchoring The caret ^ and the dollar sign $ are meta-characters that respectively match the empty string at the beginning...
(intfd);intread_data(intfd,void*buf,intlen);intwrite_data(intfd,void*buf,intlen);voidprint_usage(char*program_name);intmain(intargc,char*argv[])//./a.out /dev/ttyS3 38400 8 0 1 0{intfd;intbaud;intlen;intcount;inti;intdatabits;intstopbits;intparity;intread_or_write;if(argc ...
第二,字符(characters),用选项-c 第三,域(fields),用选项-f 示例: catcut_ch.txt 星期一 星期二 星期三 星期四 cut -c 3 cut_ch.txt 一 二 三 四 53、tr:也是替换命令 echo “I am oldboy,myqq is 49000448” | tr “,”" " #将逗号替换成空格 ...
On Linux and Unix-like operating systems, the wc command allows you to count the number of lines, words, characters, and bytes of each given file or standard input and print the result.