LINUX命令行自学笔记

tail 和 head

• see the first several lines of the file README.txt

head README.txt        # see first 10 lines of the README.txt

head -n 50 README.txt  #  see first 50 lines of the README.txt

• see last several lines of the file README.txt

tail README.txt    # see the last 10 lines of file README.txt

tail -30 README.txt | head -10   # first ten lines of the last 30 lines

Word count (wc command)

• get number of lines in the file

wc -l README.txt   # calculate how many lines in the file README.txt

split 

• 将文件分割成若干等大子文件

split -l 1000 README.txt  # split file into sub_files that have 1000 lines each

shuffle

• shuffle 数据集然后分割，机器学习做数据集的时候应该很有用！

shuf MQ2007 | split -l 1000  # shuffle and then split

cat

• 显示文件内容于命令行界面（可以接后续内容）

cat file | grep 'carneige mellon university'  # show all lines with 'cmu' to command line

uniq

• Linux uniq 命令用于检查及删除文本文件中重复出现的行列，一般与 sort 命令结合使用 --摘自‘菜鸟教程’

sort testfile1 | uniq -c  # 先对文件排序，在去重，在标准输出显示每一行重复的次数