原文發於個人獨立博客:經過《The Linux Command Line》入門linux命令行php
此書網站:The Linux Command Line ,它是免費的。css
它有中文版,並且還有一個好聽的名字:快樂的 Linux 命令行html
學習有兩種方法,一種是系統的學,一種是根據實際需求來學。兩種各有優缺點,前一種,知識不會有缺漏,對往後的融會貫通和舉一反三有好處,可是這樣慢,並且有可能不如針對性學習的精神集中。後一種,只找需求的學,可以任務完成就行,這樣快,它的缺點就是前一種的優勢。顯然通看整本書屬於第一種。node
做者寫的很好,娓娓道來,講的很清楚,就像一本故事書同樣。我很喜歡這樣的書。做者比較幽默,一些用詞看了會讓人發笑。linux
這本書的內容很淺,真的只是入門。nginx
正如做者所說,這是一場linux的journey(旅行),就把看書當旅行吧。git
如下是隨手記的,只適合本身看。github
date
cal
-calendardf
-current amount of free space on your disk drivesfree
-display the amount of free memoryexit
-closing the terminal emulator windowpwd
- Print name of current working directorycd
- Change directorycd home directory
cd - previous working directory
cd ~user_name home directory of user
. 點號表明當前文件夾
ls
- List directory contentsls -a all files
ls -l long format
ls -lt sort the result by the file's modification time
ls -lt --reverse
file
– Determine file typesql
less
– View file contentsshell
和cat的區別?參考
cp
若是文件已經存在,直接覆蓋,沒有提示,要提示用-i
mv
move (rename) files
mkdir
mkdir dir1 dir2
rm
– Remove Files And Directoriesrm -r playground # 遞歸刪除
ln
– Create Linksln myfile hard # hard link
ln -s myfile soft # symbolic link
軟連接」和「硬連接」的區別:硬連接指向磁盤區塊,軟連接指向絕對路徑。
hard links的缺點:
1.cannot span physical devices.
2.cannot reference directories, only files.
type
– Indicate how a command name is interpretedtsc@tsc:~$ type ls
ls is aliased to `ls --color=auto' # alias
tsc@tsc:~$ type cd
cd is a shell builtin # builtin
tsc@tsc:~$ type cp
cp is /bin/cp # executable program
which
– Display An Executable’s Locationtsc@tsc:~$ which cp
/bin/cp
只用於exe
help
– Get help for shell builtins
注意是shell builtin
tsc@tsc:/bin$ help cd
cd: cd [-L|[-P [-e]] [-@]] [dir]
Change the shell working directory.
理解註釋:[]
是可選,|
是互斥。
--help
– Display Usage Informationtsc@tsc:~$ mkdir --help
man
– Display a command’s manual page沒有example
tsc@tsc:~$ man ls
apropos
– Display a list of appropriate commandsinfo
– Display a command’s info entrywhatis
– Display a very brief description of a commandalias
– Create an alias for a command起別名前先檢查是否存在,用type
:
tsc@tsc:~$ type test
test is a shell builtin
使用:
alias name='string' # name後不能有空格
tsc@tsc:~$ alias foo='cd /usr; ls; cd -'
tsc@tsc:~$ foo
終端關閉後做用就消失了。
去除:
tsc@tsc:~$ unalias foo
command1; command2; command3...
tsc@tsc:~$ cd /usr; ls
help最簡單,info最詳細,man在二者之間。
cat
- Concatenate filescat file1 # 輸出文件到屏幕,沒有分頁
cat > file.txt # cat沒有參數時接受stdin
this is test.
# ctrl+d 結束
# < 接受文件輸入
tsc@tsc:~$ cat < lazy_dog.txt
sort
- Sort lines of textuniq
- Report or omit repeated lines# -d 顯示重複的
tsc@tsc:~$ ls /bin /usr/bin | sort | uniq -d | less
grep
- Print lines matching a pattern「global regular expression print」,find功能。
tsc@tsc:~$ ls /bin /usr/bin | sort | uniq | grep zip
wc
- Print newline, word, and byte counts for each file聯合使用看條目個數:
tsc@tsc:~$ ls /bin /usr/bin | sort | uniq | wc -l
head
- Output the first part of a filetail
- Output the last part of a filetee
- Read from standard input and write to standard output and files這個名字頗有意思,tee有三通管的意思,配合pipe使用,它的做用是從stdin讀入,複製到stdout和文件。
# 一方面輸出到ls.txt,一方面傳給grep
tsc@tsc:~$ ls /usr/bin/ | tee ls.txt | grep zip
I/O redirection 的做用
I/O redirection allows us to change where output goes and where input comes from.
>
重定向
tsc@tsc:~$ ls -l /usr/bin/ > ls-output.txt
tsc@tsc:~$ > ls-output2.txt # 建立一個空文件
要注意重複>
時,原來的文件會被清空。
>>
追加tsc@tsc:~$ ls -l /usr/bin >> ls-output2.txt
文件不存在會新建。
tsc@tsc:~$ ls -l /bin/usr 2> ls-error.txt
個人問題:在不知道有沒有error的狀況下,>
和2>
要如何同時執行?
有兩種方法:
# 1.老版本
# 順序很重要
tsc@tsc:~$ ls -l /bin/usr > ls-output.txt 2>&1
# 2.新,用&>
tsc@tsc:~$ ls -l /bin/usr &> ls-output.txt
tsc@tsc:~$ ls -l /bin/usr &>> ls-output.txt # 追加
tsc@tsc:~$ ls -l /usr/bin | less
千萬不要把>
用成|
,否則有些後果很嚴重。
tsc@tsc:~$ ls /bin /usr/bin | sort | less
這節講expansion, 就是*
、~
之類的,本質就是變量。
echo
– Display a line of textIt prints out its text arguments on standard output
tsc@tsc:~$ echo this is a test
this is a test
tsc@tsc:~/playground$ echo ~
/home/tsc
形式:
$((expression))
tsc@tsc:~/playground$ echo $((2+2))
4
brace expansion
括號中間不能有空格。
用途:批量建立有順序的文件。
Parameter Expansion
Command Substitution
command的結果也能夠做爲expansion
echo $(ls)
Double Quotes
「$」, 「\」 (backslash), and 「`」 (backquote) 失效,可是parameter expansion, arithmetic expansion, and command substitution 仍有效。
注意區別:
echo $(cal)
echo "$(cal)"
空格、tab、換行符都被用來分割,雙引號則抑制。因此前一個命令不會換行,後一個會。
Single Quotes
抑制全部expansions
escape character
和雙引號一塊兒使用,抑制部分符號
這節講鍵盤技巧,提升效率。主要是command line和history的技巧。command line的:移動,刪除。history的上下一個命令。
clear
– Clear the screen
history
– Display the contents of the history list
Cursor Movement
completion
補全
history
history expansion-使用history中1209行的命令:
tsc@tsc:~$ !1209
思考:多用戶爲何存在?想一想計算中心。
多用戶存在要解決的問題:
1.一個用戶的錯誤操做不能使計算機crash
2.一個用戶不能影響其餘用戶
/etc/passwd
User accounts .
/etc/group
groups
/etc/shadow
user's password
Owner Group World
id
– Display user identity$ id
uid=1000(tsc) gid=1000(tsc) groups=1000(tsc),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),128(sambashare)
# root
# id
uid=0(root) gid=0(root) groups=0(root)
chmod
– Change File Mode$ chmod 600 foo.txt
umask
– Set Default Permissions
su
– Run A Shell With Substitute User And Group IDs
默認是superuser
$ su -
exit
sudo
– Execute A Command As Another User
糾正本身的認識,su,sudo是改變用戶的,不必定是super,默認纔是。
chown
– Change File Owner And Group
chgrp
– Change Group Ownership
passwd
- change user password
進程
Processes are how Linux organizes the different programs waiting for their turn at the CPU.
ps
- report a snapshot of the current processes.
top
- display Linux processes
&
- Putting A Process In The Background
jobs
- list the jobs that have been launched from our terminal.
fg
- Returning A Process To The Foreground
爲何要回到前臺來?後臺的程序不受terminal的控制。
Ctrl-z
- Stopping (Pausing) A Process
注意和ctrl-c的區別,c是結束。
bg
- resume the program’s execution in the background
kill
- 「kill」 processes
killall
- kill processes by name
halt
poweroff
reboot
shutdown
什麼是environment?
configuration的做用:store program settings
printenv
- print all or part of environment# 全部environment
tsc@tsc:~$ printenv | less
# 某一個environment
tsc@tsc:~$ printenv USER
tsc@tsc:~$ echo $HOME
printenv
顯示的一些常見變量:
SHELL
PATH # 全部的,最新的
set
will show both the shell and environment variables
printenv
和set
的區別
printenv
只顯示environment variables,set
顯示shell和environment variables.
追加
PATH=$PATH:$HOME/bin
export
tells the shell to make the contents of PATH available to child processes of this shell.
啓動順序
Login Shell Sessions :
/etc/profile # global
~/.bash_profile
~/.bash_login # 若是上面那個不存在,讀這個
~/.profile # 若是上面那個不存在,讀這個
.profile
文件中有PATH,而且將$HOME/bin
添加上了,因此啓動系統後$HOME/bin
中的命令是直接能夠用的。$HOME
是用戶目錄。
Non-Login Shell Sessions :
/etc/bash.bashrc # global
~/.bashrc # user's
Login和Non-Login的區別?
參考,
PATH的做用
命令從中找。
改環境變量時改哪一個文件?
.profile
:
add directories
define additional environment variables
.bashrc
:
everything else
有兩種:
1.graphical :gedit
2.text based :nano, vi, emacs
ctrl-x : exit
ctrl-o : save, write out
# : comments
.bashrc
生效首先要知道原理,啓動流程,在session一開始纔會read .bashrc
,因此須要重啓terminal纔會生效。固然,能夠強行重讀.bashrc
,用source
命令:
source .bashrc
why vi?
always available
lightweight and fast
vi 操做
:q
:q! # 強制退出
i # insert
esc # to command mode
:w # save ,有:的命令叫ex command
# move
h, j, k, l
ctrl-f/b
numberG
gg # 第一個字符
G last line of the file
0 (zero) 行首
^ To the first non-whitespace character on the current line.
$ end of current line
w beginning of next word or punctuation
W ignoring punctuation
b beginning of previous word or punctuation
B ignoring punctuation
# edit
u # undo last change
i # insert
# append
a # append, i是前插
A # 直接到最後append
# opening a line
o # 新建一行在下面
O # 新建一行在上面
# delete
x # current character
3x
dd # current line,d有cut的做用
dw #
dW # ignoring punctuation
d$ # current cursor to end
d0 # current cursor to beginning
dG # current cursor to end of file
d20G # current cursor to 20 line,不是要刪除20行
5dd # 5行
# Cutting, Copying, And Pasting
p # 小寫粘貼在後一行(dd),普通在光標前
P # 大寫粘貼在前一行(dd),普通在光標後
p # paste after cursor
P # upper case, paste before cursor
# copy
yy # copy current line
5yy # copy 5 line
yW # ignoring punctuation
yw #
y$ # current cursor to end of line
y0 # current cursor to beginning of line
y^ # current cursor to first non-whitespace char
yG # current cursor to last line of file
y20G # current cursor to 20th line
# redo,undo
u # undo
ctrl+r # redo
J # join line
# search, replace
fa # 行內搜索a,按;繼續搜索
/ # 文件內搜索,n繼續
:%s/line/Line/g # 替換
:%s/line/Line/gc # 有提醒的替換
%表明對全部內容進行操做
:1,2s/line/Line/gc # 對1-2行進行操做
Ctrl-e, Ctrl-y # Scroll down and scroll up
The leading tilde characters (」~」) indicate that no text exists on that line.
modal editor
command mode
You can change the case of text:
Toggle case 「HellO」 to 「hELLo」 with g~
then a movement.
Uppercase 「HellO」 to 「HELLO」 with gU
then a movement.
Lowercase 「HellO」 to 「hello」 with gu
then a movement.
Alternatively, you can visually select text then press ~
to toggle case, or U
to convert to uppercase, or u
to convert to lowercase.
# 到行尾
$ 反:0
A 反:I
Word movement: w, e, b
Linux vi and vim editor: Tutorial and advanced features
就是這個:
tsc@tsc:~$
更改它:
tsc@tsc:~$ PS1="<\u@\h \w>\$ "
<tsc@tsc ~>$
\u # username of the current user.
\h # Hostname of the local machine minus the trailing domain name.
\w # Name of the current working directory.
\$ # This displays a 「$」 character unless we have superuser privileges. In that case, it displays a 「#」 instead.
改顏色:
經過escape code 實現,escape code 的開頭是八進制的033 ,例子:
\033[0;30m
\033是開頭
0 是optional character attribute,0表明text color是normal,1是bold
30m 是instruction
tsc@tsc:~$ PS1="\[\033[0;31m\]<\u@\h \w>\$\[\033[0m\] " \033[0m # 表明結束脩改
要知道package是什麼,如何install, remove, update
linux的哪一個發行版纔是最好的?考慮的因素不是界面,而是:
1.packaging system
2.vitality of the distribution’s support community
Debian 「.deb」 camp
Red Hat 「.rpm」 camp
Packaging System Distributions (Partial Listing)
Debian Style (.deb) Debian, Ubuntu, Linux Mint, Raspbian
Red Hat Style (.rpm) Fedora, CentOS, Red Hat Enterprise Linux, OpenSUSE
package files
shared libraries
軟件都是有依賴的,被依賴的就放在這裏
dependency
package tool
分爲high, low-level兩種,
high:metadata search, dependency
low-level: installing, removing
Red Hat系列使用同一low-lvel program(rpm), high-level則不一樣,yum使用者:Fedora, Red Hat Enter, CentOS.
Distributions | Low-Level Tools | High-Level Tools |
---|---|---|
Debian-Style | dpkg | apt-get, aptitude |
Fedora, Red Hat, Enterprise Linux, CentOS | rpm | yum |
- 查找和安裝package的方法
- What is the difference between apt-get update and upgrade?
attaching the device to the file system tree.
mount
– Mount a file system 沒有參數時,顯示已經mounted的文件系統。
如何看?device on mount_point type file_system_type (options).
free
- Display amount of free and used memory in the system
partition number 是什麼?
Unable to enumerate USB device under virtualbox
usb3.0插的3.0的口上在vm中讀不出來,改插在2.0的口上就能夠,真是。。。
磁盤、分區及Linux文件系統 [Disk, Partition, Linux File System]
inode的做用:實現文件存儲的關鍵。
tail
的妙用
# ubuntu
tail -f /var/log/syslog
實時觀察系統在作什麼。
fsck
- check and repair a Linux filesystemIP Addresses, Host Names, and Domain Names
明白host name與domain name的區別。
ping
, ping6
- send ICMP ECHO_REQUEST to network hosts
traceroute
- print the route packets trace to network host
ip
- show / manipulate routing, devices, policy routing and tunnels
DHCP (Dynamic Host Configuration Protocol)
netstat
- Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships
ftp
— Internet file transfer program
ftp是明文傳輸。
Wget
- The non-interactive network downloader.
ssh
rlogin and telnet 和ftp有同樣的缺陷。
ssh解決了兩大問題:First, it authenticates that the remote host is who it says it is (thus preventing so-called 「man in the
middle」 attacks), and second, it encrypts all of the communications between the local and
remote hosts.
ssh root@ip -p 端口號
windows下的ssh軟件
PuTTY
找文件。
locate
- find files by name
locate查找的數據庫是如何更新的?由updatedb 程序更新,能夠手動更新。
find
- search for files in a directory hierarchy
$ find ~ -type f | wc
# 文件名有jpg,大小大於1M
$ find ~ -type f -name "*.jpg" -size +1M | wc -l
$ find ~ \( -type f -not -perm 0600 \) -or \( -type d -not -perm 0700 \)
順序很重要。
把查找的結果做爲命令的輸入參數
$ find ~ -type f -name 'foo*' -exec ls -l '{}' ';'
$ find ~ -type f -name 'foo*' -exec ls -l '{}' +
$ find ~ -type f -name 'foo*' -print | xargs ls -l
{} is a symbolic representation of the current pathname
semicolon is a required delimiter indicating the end of the command.
+
:the system only has to execute the ls command once
$ find ~ -type f -name '*.jpg' -print0 | xargs --null ls -l
touch
- change file timestamps
文件不存在時會建立。
stat
- display file or file system status
which is a kind of souped-up version of ls.
管理大量的文件-壓縮。
本節講3個內容:
compression
archiving
synchronization
gzip, gunzip, zcat
- compress or expand filesgzip
壓縮,gunzip
解壓。
gzip
會替換原來的文件。
zcat
- equivalent to gunzip
with the -c
optionbzip2, bunzip2
- a block-sorting file compressortar
-tape archive
.tar or .tgz, which indicate a 「plain」 tar archive and a gzipped archive, respectively.
# c create
$ tar cf playground.tar playground
# t list
$ tar tf playground.tar
# x extract
$ tar xf ../playground.tar
# r append
# extract a single file
$ tar xf archive.tar pathname
注意區分mode與option,c是mode,f是option。
mode要先寫。
studout或者stdin就能夠用減號(-)來替代
使用zcat
能夠查看*.gz
文件內容,使用bzcat
能夠直接查看*.bz2
文件.
$ ssh root@xxx.xxx.xx.xx -p 端口號 'tar cf - filename' | tar xf -
root@xxx.xxx.xx.xx's password:
先tar,傳回來再導出。
zip
- 既壓縮也歸檔zip
,unzip
的做用是交換indows文件,linux用tar
,gzip
rsync
- 備份與同步rsync options source destination
$ rsync -av playground foo
後面幾章都是關於文字處理的。先講regular expression.
metacharacters是^ $ . [ ] { } - ? * + ( ) | \
,其他就是literal characters。
就是點號,the dot or period character
The caret (^
) (只匹配行首出來的)and dollar sign ($
) (只匹配行尾出現的)
$ grep -h '^zip' dirlist*.txt
$ grep -h 'zip$' dirlist*.txt
$ grep -h '^zip$' dirlist*.txt
$ grep -h '.zip' dirlist*.txt
$ grep -i '^..j.r$' /usr/share/dict/words
[]
用來只匹配一個字符。
$ grep -h '[bg]zip' dirlist*.txt
^ : negation,只在第一個位置時有效
$ grep -h '[^bg]zip' dirlist*.txt # 注意出現的位置,表示取反
- : range
$ grep -h '^[A-Za-z0-9]' dirlist*.txt
# 要匹配-(短橫線),就把它放到第一位
$ grep -h '[A-Z]' dirlist*.txt
$ grep -h '[-AZ]' dirlist*.txt
出現的緣由:posix和ASCII不同。
[]
是單個,它(|
)是string
$ echo "AAA" | grep -E 'AAA|BBB|CCC'
$ grep -Eh '^(bz|gz|zip)' dirlist*.txt
匹配的個數
?
- Match An Element Zero Or One Time ,一個字符出現的次數,和word裏面的?不一樣,word裏面表明任意一個字符,這裏的?不能單獨使用,要跟在一個字符後面。
$ echo "(555) 123-4567" | grep -E '^\(?[0-9][0-9][0-9]\)? [0-9][0-9][0-9]-[0-9][0-9][0-9][0-9]$'
*
- Match An Element Zero Or More Times
$ echo "This works." | grep -E '[[:upper:]][[:upper:][:lower:] ]*\.'
和?同樣,前面要有字符。
+
- Match An Element One Or More Times
至少出現一次。
$ echo "This that" | grep -E '^([[:alpha:]]+ ?)+$'
{ }
- Match An Element A Specific Number Of Times
$ echo "(555) 123-4567" | grep -E '^\(?[0-9]{3}\)? [0-9]{3}-[0-9]{4}$'
find
使用reg$ find . -regex '.*[^-_./0-9a-zA-Z].*'
# 反 0-無窮個字符
$ locate --regex 'bin/(bz|gz|zip)'
注意它們的區別,在vi中reg是basic
# less
/^\([0-9]{3}\) [0-9]{3}-[0-9]{4}
# vi
/([0-9]\{3\}) [0-9]\{3\}-[0-9]\{4\}
真是一切皆文件。
$ cat -A foo.txt # 顯示全部符號,包括控制符
$ cat -ns foo.txt # n顯示行號,s抑制多餘的空行
$ sort > foo.txt
c
b
a
# 多個文件
$ sort file1.txt file2.txt file3.txt > final_sorted_list.txt
du
- estimate file space usage
$ du -s /usr/share/* | head # 顯示前10個
$ du -s /usr/share/* | sort -nr | head # 大到小排序後顯示前10個
按指定列排序(k):
$ ls -l /usr/bin | sort -nr -k 5 | head
多個key排序:
$ sort --key=1,1 --key=2n distros.txt
# 一個field內多個排序:
$ sort -k 3.7nbr -k 3.1nbr -k 3.4nbr distros.txt
指定分割符:
$ sort -t ':' -k 7 /etc/passwd | head
$ sort foo.txt | uniq
# 取第3列
$ cut -f 3 distros.txt
每一個field的長度可能不一樣,若是要取全部行中時間中的年,就不可能用字符位置去表示。而先把field取出來,就規整了。
$ cut -f 3 distros.txt | cut -c 7-10
$ expand distros.txt | cut -c 23-
$ cut -d ':' -f 1 /etc/passwd | head
adds one or more columns of text to a file
$ sort -k 3.7nbr -k 3.1nbr -k 3.4nbr distros.txt > distros-by-date.txt
$ cut -f 1,2 distros-by-date.txt > distros-versions.txt
$ cut -f 3 distros-by-date.txt > distros-dates.txt
$ paste distros-dates.txt distros-versions.txt
It joins data from multiple files based on a shared key field.
$ join distros-key-names.txt distros-key-vernums.txt | head
$ comm file1.txt file2.txt
# -n 抑制列
$ comm -12 file1.txt file2.txt
$ diff file1.txt file2.txt
# context format 看兩個各自都有什麼,沒有什麼
$ diff -c file1.txt file2.txt
# unified format 看從舊到新的變化
$ diff -u file1.txt file2.txt
apply changes to text files
用來更新文件,好比代碼。
$ diff -Naur file1.txt file2.txt > patchfile.txt
$ patch < patchfile.txt
轉換
$ echo "lowercase letters" | tr a-z A-Z
LOWERCASE LETTERS
# 多對一的轉換
$ echo "lowercase letters" | tr [:lower:] A
# squeeze
$ echo "aaabbbccc" | tr -s ab
abccc
stream editor
# search-and-replace
$ echo "front" | sed 's/front/back/'
# 誰跟在command後面就是delimiter
$ echo "front" | sed 's_front_back_'
# 指定要處理的行數
$ echo "front" | sed '1s/front/back/'
# p:打印出來
# -n: not to print every line by default
$ sed -n '1,5p' distros.txt
$ sed -n '/SUSE/p' distros.txt
$ sed -n '/SUSE/!p' distros.txt
# 通常出輸出到屏幕,用i原地
$ sed -i 's/lazy/laxy/; s/jumped/jimped/' foo.txt
$ sed 's/\([0-9]\{2\}\)\/\([0-9]\{2\}\)\/\([0-9]\{4\}\)$/\3-\1-\2/' distros.txt
$ echo "aaabbbccc" | sed 's/b/B/'
$ echo "aaabbbccc" | sed 's/b/B/g'
拼寫檢查
$ aspell check foo.txt
# -H (HTML) checking-mode option
$ aspell -H check foo.txt
改完了會產生一個bak文件,存在原來的文本。
講文本輸出格式。
顯示行號
$ nl distros.txt | head
# 和cat -n 同樣
$ sort -k 1,1 -k 2n distros.txt | sed -f distros-nl.sed | nl
$ echo "The quick brown fox jumped over the lazy dog." | fold -w 12
# 不打斷單詞
$ echo "The quick brown fox jumped over the lazy dog." | fold -w 12 -s
it fills and joins lines in text while preserving blank lines and indentation.
$ fmt -w 50 fmt-info.txt | head
$ fmt -cw 50 fmt-info.txt
# 一行若是不足50個字符,會把第二行的補過來
# 只對'# '開頭的行操做
$ fmt -w 50 -p '# ' fmt-code.txt
used to paginate text.
# l:page length
# w:width
$ pr -l 15 -w 65 distros.txt
首尾會有空行。
「print formatted」
使用:printf 「format」 arguments
$ printf "I formatted the string: %s\n" foo
$ printf "%d, %f, %o, %s, %x, %X\n" 380 380 380 380 380 380
Multiple optional components :
%[flags][width][.precision]conversion_specification
tex後來取代了troff.
$ zcat /usr/share/man/man1/ls.1.gz | head
$ man ls | head
$ zcat /usr/share/man/man1/ls.1.gz | groff -mandoc -T ascii | head
# 存爲postscript到桌面
$ zcat /usr/share/man/man1/ls.1.gz | groff -mandoc > ~/Desktop/foo.ps
# ps轉pdf
$ ps2pdf ~/Desktop/foo.ps ~/Desktop/ls.pdf
介紹了ps的由來。
CUPS (Common Unix Printing System) :provides print drivers and print-job management
Ghostscript: a PostScript interpreter, acts as a RIP.
pr is used to adjust text to fit on a specific page size, with optional page headers and margins.
# 3列
$ ls /usr/bin | pr -3 -w 65 | head
CUPS 有兩種printing,lpr, lp.
$ ls /usr/bin | pr -3 | lpr
lpr: Error - no default destination available.
# 查看printer
$ lpstat -a
lpstat: No destinations added.
「Anything to PostScript.」
$ ls /usr/bin | pr -3 -t | a2ps -o ~/Desktop/ls.ps -L 66 -R
# 查詢printer狀態
$ lpstat -a
$ lpstat -a
$ lpq
PDF is ready
no entries
compile
linker,解決共享問題,用共享庫。
$ which gcc
/usr/bin/gcc
$ mkdir src
$ cd src
$ ftp ftp.gnu.org
Name (ftp.gnu.org:me): anonymous
ftp> cd gnu/diction
ftp> ls
ftp> get diction-1.11.tar.gz
ftp> bye
$ tar xzf diction-1.11.tar.gz
# 先查看是否是在一個文件夾裏,以避免解壓散開
$ tar tzvf diction-1.11.tar.gz | less
共享的頭文件在/usr/include
,The header files in this directory were installed when we installed the compiler.
通常須要兩步。
# 因爲script不在默認的目錄,須要./告訴shell它在當前目錄
$ ./configure
config.status: creating Makefile
config.status: creating diction.1
config.status: creating diction.texi
config.status: creating diction.spec
config.status: creating style.1
config.status: creating test/rundiction
config.status: creating config.h
Makefile is a configuration file that instructs the make program exactly how to build the program. Without it, make will refuse to run.
$ make
$ sudo make install
#!
shebang,指明interpreter,每一個script開頭都應該加這行。
$ chmod 755 hello_world
owner的權限是x就能夠了。755全部人能夠執行,700只有owner能夠執行。必須是可讀的。
$ ./hello_world
必需要加上./
,由於文件位置的問題。自動識別的命令的目錄都寫在了PATH中,能夠查看它:
$ echo $PATH
在.bashrc
(它在~
中)中添加:
# 把~/bin添加在PATH的前面
export PATH=~/bin:"$PATH"
# 在當前terminal中生效
$ . .bashrc
# 或者
$ source .bashrc
~/bin : 本身用
/usr/local/bin : 同一個系統多人用
/usr/local/sbin: 系統管理員用
/usr/local: locally supplied software,
就是\
:syntax on
:set hlsearch
:set tabstop=4
:set autoindent
永久:
寫在~/.vimrc,沒有就建立
shell是動態語言
uppercase letters to designate constants and lower case
letters for true variables.
$ vim ~/bin/sys_info_page
$ chmod 755 ~/bin/sys_info_page
$ sys_info_page
$ sys_info_page > sys_info_page.html
$ firefox sys_info_page.html
uppercase letters to designate constants and lower case letters for true variables.
Note that in an assignment, there must be no spaces between the variable name, the equals sign, and the value.
a=z # Assign the string "z" to variable a.
b="a string" # Embedded spaces must be within quotes.
c="a string and $b" # Other expansions such as variables can be
# expanded into the assignment.
d="$(ls -l foo.txt)" # Results of a command.
e=$((5 * 7)) # Arithmetic expansion.
f="\t\ta string\n" # Escape sequences such as tabs and newlines.
大括號的做用
$ filename="myfile"
$ touch "$filename"
$ mv "$filename" "$filename1"
mv: cannot move 'myfile' to '': No such file or directory
$ mv "$filename" "${filename}1"
command << token
text
token
# shell example
cat << _EOF_
<HTML>
<HEAD>
<TITLE>$TITLE</TITLE>
</HEAD>
</HTML>
_EOF_
# terminal example
$ cat << _EOF_
> $foo
> "$foo"
> '$foo'
> \$foo
> _EOF_
講程序設計的思想。
兩種形式:
function name {
commands
return
}
and the simpler (and generally preferred) form:
name () {
commands
return
}
in order for function calls to be recognized as shell functions and not interpreted as the names of external programs, shell function definitions must appear in the script before they are called.
要加local
funct_1 () {
local foo # variable foo local to funct_1
foo=1
echo "funct_1: foo = $foo"
}
shell的if語句挺複雜的。
if commands; then
commands
[elif commands; then
commands...]
[else
commands]
fi
x=5
if [ "$x" -eq 5 ]; then
echo "x equals 5."
else
echo "x does not equal 5."
fi
程序結果後返回給系統的。查詢:
$ ls -d /usr/bin
$ echo $?
true
- do nothing, successfully
false
- do nothing, unsuccessfully
語法:
test expression
and the more popular:
[ expression ]
expression是true時返回0,不然返回1
test和[
本質上是同樣的。
使用:
#!/bin/bash
# test-file: Evaluate the status of a file
FILE=~/.bashrc
if [ -e "$FILE" ]; then
if [ -f "$FILE" ]; then
echo "$FILE is a regular file."
fi
if [ -d "$FILE" ]; then
echo "$FILE is a directory."
fi
if [ -r "$FILE" ]; then
echo "$FILE is readable."
fi
if [ -w "$FILE" ]; then
echo "$FILE is writable."
fi
if [ -x "$FILE" ]; then
echo "$FILE is executable/searchable."
fi
else
echo "$FILE does not exist"
exit 1
fi
exit # ?
When a script 「runs off the end」 (reaches end of file), it terminates with an exit status of the last command executed.
#!/bin/bash
# test-string: evaluate the value of a string
ANSWER=maybe
if [ -z "$ANSWER" ]; then
echo "There is no answer." >&2
exit 1
fi
if [ "$ANSWER" = "yes" ]; then
echo "The answer is YES."
elif [ "$ANSWER" = "no" ]; then
echo "The answer is NO."
elif [ "$ANSWER" = "maybe" ]; then
echo "The answer is MAYBE."
else
echo "The answer is UNKNOWN."
fi
[[]]
# 檢驗是否是數
if [[ "$INT" =~ ^-?[0-9]+$ ]]; then
(( ))
- Designed For Integers$ if ((1)); then echo "It is true."; fi
It is true.
if ((INT == 0));
if ((INT < 0));
if (( ((INT % 2)) == 0));
Operation test [[ ]] and (( ))
AND -a &&
OR -o ||
NOT ! !
例子:
# [[]]
if [[ "$INT" -ge "$MIN_VAL" && "$INT" -le "$MAX_VAL" ]];
# test
if [ "$INT" -ge "$MIN_VAL" -a "$INT" -le "$MAX_VAL" ];
The &&
(AND) and ||
(OR)
$ mkdir temp && cd temp
$ [[ -d temp ]] || mkdir temp
[]
和[[]]
的區別[[]]
和[]
同樣,不過有兩個新特性,:
string1 =~ regex
== operator
[[]]
和表達式之間要有空格[[ "$count" -gt 5 ]]
[[ "$count" -gt 5]] # 會報錯,執行起來會很可怕
read a single line of standard input.
read [-options] [variable...]
# -n option,suppresses the trailing newline on output
echo -n "Please enter an integer -> "
read int
read var1 var2 var3 var4 var5 # 多個
# -p prompt
read -p "Enter one or more values > "
# -t seconds
# -s Silent mode.
if read -t 10 -sp "Enter secret passphrase > " secret_pass;
Internal Field Separator
file_info=$(grep "^$user_name:" $FILE)
# 寫在一行,IFS只改變跟在後面的 command
IFS=":" read user pw uid gid name home shell <<< "$file_info"
The <<<
operator indicates a here string.
就像函數與子函數,凡是這一類都不能pip。
就是提示和if。
那應該如何作?
有3各loop
語法:
while commands; do commands; done
#!/bin/bash
# while-count: display a series of numbers
count=1
while [[ "$count" -le 5 ]]; do
echo "$count"
count=$((count + 1))
done
echo "Finished."
break
continue
和while相反
count=1
until [[ "$count" -gt 5 ]]; do
echo "$count count=$((count + 1)) done echo "Finished.
#!/bin/bash
# while-read
while read distro version release; do
printf "distro: %s\tversion: %s\treleased: %s\n" \
"$distro" \
"$version" \
"$release"
done < distros.txt
講錯誤的處理。
引號不對稱
特定符號缺失
意外的expansion
是否報錯取決於expansion的值。
雙引號的做用
# number爲空時會報錯
number=
if [ $number = 1 ]; then
# 這樣就不會了 「」=1
[ "$number" = 1 ]
Multi-word string也應該用雙引號括起來。
因此,老是用雙引號把變量括起來。
/
, null character(a zero byte)
uppercase letters A-Z, lowercase letters a-z, numerals 0-9, period (.), hyphen (-), and underscore(_).
利用echo輸出
在更改的地方加註釋,方便恢復。
case要反映edge and corner
commenting out :部分註釋
tracing :在一些關鍵點增長輸出,查看是否執行到這裏了
能夠在script的第一行加入x option:
#!/bin/bash -x
也能夠用set設置部分tracing
set -x # turn on
...
set +x # turn off
case
1 #!/bin/bash
2
3 # case-menu
4
5 clear
6 echo " 7 please select: 8 9 1. display system information 10 2. display disk space 11 3. display home space utilization 12 0. quit 13 "
14 read -p "enter selection [0-3] > "
15
16 case "$REPLY" in
17 0) echo "program terminated"
18 exit
19 ;;
20 1) echo "hostname: $HOSTNAME"
21 uptime
22 ;;
23 2) df -h
24 ;;
25 3) if [[ "$(id -u)" -eq 0 ]]; then
26 echo "home space utilization (all users)"
27 du -sh /home/*
28 else
29 echo "home space utilization ($USER)"
30 du -sh "$HOME"
31 fi
32 ;;
33 *) echo "invalid entry" >&2
34 exit 1
35 ;;
36 esac
講處理command的option
$0
是當前命令的路徑。
注意它的含義:
Note that $0 always contains the full pathname of the first item on the command line (i.e., the name of the program) and does not contain the name of the shell function as we might expect.
是整個路徑,不是命令的名字。
大於9時用大括號括起來。
$#
讓$1
下次變成$2
,全部參數都移動,$#
減1
去除文件名前面的字符,只要文件名。
positional parameter也能夠用在function中
Difference between echo -e 「」 and echo $「」
e的意思就是擴展,支持轉義,e和$
支持的符號部分不相同。
$*
和$@
的區別
不加雙引號時是同樣的,遇到空格就拆分,加雙引號時不同,$*
會將全部參數放到一個字符串中,$@
會將每一個輸入的參數分別看成參數,也就是不區分輸入時的空格。
$@
常常用。
講for
# 兩種風格
for variable [in words]; do
commands
done
# c語言的
for (( expression1; expression2; expression3 )); do
commands
done
例子:
[me@linuxbox ~]$ for i in A B C D; do echo $i; done
Create list:
itscs-MacBook-Pro:~ itsc$ for i in {A..D}; do echo $i; done
# 文件列表 pathname expansion
itscs-MacBook-Pro:learnCommandLine itsc$ for i in dis*.txt; do echo "$i"; done
變量是其中的一種
$a
${a}
a="foo"
echo "${a}_file" # 和其它字符相連時防止造成不存在的變量
parameter爲空或者不存在就用word,存在就用它本身。
${parameter:-word}
和上面基本同樣,區別:要賦值。
${parameter:=word}
unset和empty就發發送word到error
${parameter:?word}
${parameter:+word}
${#parameter} # 換成長度
$ foo="This string is long."
$ echo "'$foo' is ${#foo} characters long. 'This string is long.' is 20 characters long ${parameter:offset} ${parameter:offset:length} [me@linuxbox ~]$ foo="This string is long." [me@linuxbox ~]$ echo ${foo:5} string is long. [me@linuxbox ~]$ echo ${foo:5:6} string 刪除一部分 ${parameter#pattern} ${parameter##pattern} [me@linuxbox ~]$ foo=file.txt.zip [me@linuxbox ~]$ echo ${foo#*.} txt.zip [me@linuxbox ~]$ echo ${foo##*.} zip 反着刪除 ${parameter%pattern} ${parameter%%pattern} [me@linuxbox ~]$ foo=file.txt.zip [me@linuxbox ~]$ echo ${foo%.*} file.txt [me@linuxbox ~]$ echo ${foo%%.*} file 替換 ${parameter/pattern/string} ${parameter//pattern/string} ${parameter/#pattern/string} ${parameter/%pattern/string}
能夠用來作什麼?好比數據庫的查找,匹配的時候把輸入和數據庫中的都統一大小寫。
itscs-MacBook-Pro:learnCommandLine itsc$ echo $((3.3+4.2))
-bash: 3.3+4.2: syntax error: invalid arithmetic operator (error token is ".3+4.2")
解決:perl, awk.書裏用最簡單的bc
爲何連浮點運算都不支持?真是麻煩。
Single value
[me@linuxbox ~]$ a[1]=foo
[me@linuxbox ~]$ echo ${a[1]}
foo
[me@linuxbox ~]$ declare -a a
# assign
name[subscript]=value
name=(value1 value2 ...)
[me@linuxbox ~]$ days=(Sun Mon Tue Wed Thu Fri Sat)
[me@linuxbox ~]$ days=([0]=Sun [1]=Mon [2]=Tue [3]=Wed [4]=Thu [5]=Fri [6]=Sat)
[me@linuxbox ~]$ animals=("a dog" "a cat" "a fish")
[me@linuxbox ~]$ for i in ${animals[*]}; do echo $i; done
[me@linuxbox ~]$ for i in ${animals[@]}; do echo $i; done
[me@linuxbox ~]$ for i in "${animals[*]}"; do echo $i; done
[me@linuxbox ~]$ for i in "${animals[@]}"; do echo $i; done
因此須要有方法知道哪些位置上有值
[me@linuxbox ~]$ foo=([2]=a [4]=b [6]=c)
[me@linuxbox ~]$ for i in "${foo[@]}"; do echo $i; done
a
b
c
[me@linuxbox ~]$ for i in "${!foo[@]}"; do echo $i; done
2
4
6
$ foo=(a b c)
$ foo[100]=e
$ echo ${foo[@]}
a b c e
$ foo+=(k l)
$ echo ${foo[@]}
a b c e k l
$ for i in "${foo[@]}"; do echo $i; done
a
b
c
e
k
l
$ for i in "${!foo[@]}"; do echo $i; done
0
1
2
100
101
102
subscript不是連續的
下標能夠是字符
講一些不經常使用的,在特定場景下使用的
Group command:
{ command1; command2; [command3; ...] }
Subshell:
(command1; command2; [command3;...])
它們是作什麼的?
manage redirection
{ ls -l; echo "Listing of foo.txt"; cat foo.txt; } > output.txt
(ls -l; echo "Listing of foo.txt"; cat foo.txt) > output.txt
結合pip
{ ls -l; echo "Listing of foo.txt"; cat foo.txt; } | lpr
due to the way bash implements
group commands, the braces must be separated from the commands by a space and the
last command must be terminated with either a semicolon or a newline prior to the closing brace.
subshell和它的名字同樣,返回時enviroment會丟失,因此通常狀況下用group.
echo "foo" | read
echo $REPLY # 這就是subshell的例子,reply是空的
commands in pipelines are always executed in subshells
用來解決subshell的問題
read < <(echo "foo")
echo $REPLY
舉個打電話的例子:
阻塞/同步:打一個電話一直到有人接爲止
非阻塞:打一個電話沒人接,每隔10分鐘再打一次,知道有人接爲止
異步:打一個電話沒人接,轉到語音郵箱留言(註冊),而後等待對方回電(call back)看起來異步是最高效,充分利用資源,能夠想像整個系統能支持大規模併發。但問題是調試很麻煩,不知道何時call back。
create a connection between two processes and can be
used just like other types of files.
named pipe是一個文件起着pipe的做用
[me@linuxbox ~]$ mkfifo pipe1
[me@linuxbox ~]$ ls -l pipe1
prw-r--r-- 1 me me 0 2009-07-17 06:41 pipe1
# terminal 1
[me@linuxbox ~]$ ls -l > pipe1
# terminal2
[me@linuxbox ~]$ cat < pipe1
[[:upper:]]
哪一節的?
每一個文件夾下的.
和..
的做用?爲何必需要有它們?
它們表明當前和前一級目錄,這個你們都知道,能夠爲何要有它們?設計原理是什麼?
參考:SO,只說了有,沒有說什麼爲何。
shell中各類括號[]、[[]]的做用與區別?
參考。
磁盤、分區及Linux文件系統 [Disk, Partition, Linux File System]
IDE、SATA、SCSI、SAS、FC、SSD硬盤類型介紹
Understand synopsis in manpage
能夠直接在命令man man
中看。
vi color
cd ~
vi .vimrc
syntax on
colorscheme desert
添加到vimrc中即永久:
set tabstop=4
標準錯誤輸出>&2
輸出到哪了?
屏幕。
vim color
/usr/share/vim/vim74/colors/
我以爲還不錯的:
koehler
industry
murphy
ron
How to make ls sort by file extension and then name?
ls -lX
Reveal the line numbers:
:set number
then
:5,$s/^/#/g comment
or this:
:5,$s/^/#/ uncomment
Vim: copy selection to OS X clipboard still fail to work
To check if your Vim has clipboard support: vim --version | grep -i clipboard
. You should see +clipboard
. If you see -clipboard
your Vim was compiled without clipboard support…
itscs-MacBook-Pro:learnCommandLine itsc$ vim --version | grep -i clipboard
-clipboard +job +path_extra +user_commands
+eval -mouse_dec +statusline -xterm_clipboard
個人是減號,說明不支持。
Getting Vim with +clipboard
support
要先裝Homebrew,裝完後的vim在 /usr/local/bin/vim,原來的在/usr/bin
,也存在,只不過PATH中,local的在前面,命令會先用它。
echo $1
echo "$1"
echo '$1'
$ ./longest words
words
words
$1
雙引號與無引號在這裏是同樣的,雙引號的做用體如今字符串爲空的時候,爲空的時候是空字符串,能夠判斷,而無引號就麻煩了,好比等號,一邊爲空會報錯,說等號是個二元操做符兩邊都要有值。單引號的做用就是禁止轉義,所有爲字符串。
$#
添加到Shell的參數個數
$! shell parameter, which will always contain the process ID of the
last job put into the background.