Linux shell命令(2) - cat/cut/paste/sed/tr/grep/sort/uniq

who

alluserscurrentlyloggedintothesystem
cat

examinethecontentsofafile
wc-l

wc-w

wc-c

getacountofthetotalnumberoflines,words,andcharactersofinformationcontainedinafile

cut

cut-ccharsfile

$who

rootconsoleFeb2408:54

stevetty02Feb2412:55

georgetty08Feb2409:15

dawntty10Feb2415:55

$who|cut-c1-8Extractthefirst8characters

root

steve

george

dawn

$

$who|cut-c1-8,18-

rootFeb2408:54

steveFeb2412:55

georgeFeb2409:15

dawnFeb2415:55

$

-dand-foptions

以-d指定分界符将参数分成多个field，-f指定哪几个field

不指定分界符，则以tab为分界符

$cat/etc/passwd

root:*:0:0:TheSuperUser:/:/usr/bin/ksh

cron:*:1:1:CronDaemonforperiodictasks:/:

bin:*:3:3:Theownerofsystemfiles:/:

uucp:*:5:5::/usr/spool/uucp:/usr/lib/uucp/uucico

asg:*:6:6:TheOwnerofAssignableDevices:/:

steve:*:203:100::/users/steve:/usr/bin/ksh

other:*:4:4:Neededbysecureprogram:/:

$cut-d:-f1/etc/passwdExtractfield1

root

cron

bin

uucp

asg

steve

other

$cut-d:-f1,6/etc/passwdExtractfields1and6

root:/

cron:/

bin:/

uucp:/usr/spool/uucp

asg:/

steve:/users/steve

other:/

$

grep

greppatternfiles搜索模式串

*，？都可运用到模式串和文件名

正则表达式例子：

grep'[A-Z]'list	Linesfromlistcontainingacapitalletter
grep'[0-9]'data	Linesfromdatacontaininganumber
grep'[A-Z]...[0-9]'list	Linesfromlistcontainingfive-characterpatternsthatstartwithacapitalletterandendwithadigit
grep'\.pic$'filelist	Linesfromfilelistthatendin.pic

grep–i忽略匹配大小写

grep-v找出不匹配模式串的行

grep-l仅列出包含模式串的文件

grep-n额外给出匹配的行号

sort

排序

sort-u去除重复项

sort-r逆向排序

sort-o重定向到文件sortnames-osorted_names等价于sortnames-o>sorted_names

sort-n算术排序，而非字符排序

sort+1n跳过第1个field，然后算术排序

sort-t指定分界符来分隔field,通常sort+1n这类都默认以space或tab为分隔符