BashPragramming.pdfBash脚本学习宝典，简单易懂，章节丰富，包含基本bash知识

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详细说明：Bash脚本学习宝典，简单易懂，章节丰富，包含基本bash知识，适合快速上手Bash overview BASH is an acronym for Bourne-Again SHell, punning on the name of the bourne shell that it replaces and on the term born again"that denotes spiritual rebirth in contemporary american Christianity Bash is a Unix shell and command language written by Brian Fox for the gnu project as a free software replacement for the bourne shel First released in 1989 it has been distributed widely as the default login shell for Linux distributions and apple's macoS ( formerly OS X) Latest version of bash is 4,4 Bash Overview(cont Bash is a command processor that typically runs in a text window, where the user types commands that cause actions. Bash can also read commands from a file, called a script Like all Unix shells, it supports filename globbing (wildcard matching), piping, here documents, command substitution variables and control structures for condition-testing and iteration the keywords syntax and other basic features of the language are all copied from sh. Other features, e.g., history are copied from csh and ksh Bash is a posix shell. but with a number of extensions Bash Programming Special Parameters Parameter Meaning S? Exit status ss PId of the shell s! Pid of the job most recently placed into the background $# The number of positional parameters so The name of the shell or shell script s The absolute pathname of the shell Bash Programming(2 Special Parameters Examp bash-4.3 bash-4.3$ 800 AMD64 bash-4.3$ cat-n/tmp/foo. sh File Edit View Search Terminal Help 1 #!/bin/bash bash-4.3$ bash /tmp/foo. sh 2echo\$≡$ =/usr/bin/bash 3echo\$0=$0 $0=/tmp/foo. sh 4et:123456789as#=10 5echo\$#=$# 1=1$9=9$10=a 6eho\$1=199=9510=$105=9651 7echo\$\$=$$ $!=9652 8 sleep 5 bash-4.3$ echo $ 9echo\$!=$! 99 10 exit 99 bash-4.3s bash-4.3$ Bash Programming( 3) Parameters Parsing S# and so,51,…,Sn S#: The number of positional parameters so, $1, Sn: Positional parameters fn>=10,useS{n}e.g.S{10}S{11} S*vs S Unquoted s* is the same as s “S*"V.S.“S S*" is equivalent to“S1S2…Sn S" is equivalent to“S1"“s2”…."Ssn Bash Programming(4 Parameters Parsing(2) shift [n The positional parameters from Sn+1.are renamed $1 Default n is 1 Often used in functions, or shift s(( oPtind-1 ))after getopts is used getopts Don't have to manually parse parameters, use getopts instead OPTARG is the value of the last option argument OPTIND is the index of the last option argument It also supports long options Bash Programming(5 Variable Assignments An assignment token is one of varname=word varname+=word varnamelsubscript]=word varnamelsubscript]+=word No space is permitted between varname and the =+=or between =/+= and word The [] acts to quote special characters subscript can be string or arithmetic Bash Programming(6) Variable Assignments(2) The + form is for appending to a variable varname If var type is string, new value is appended to the existing string If var type is arithmetic, new value is added to the existing arithmetic value If var type is indexed array new value is appended to the existing indexed array If var type is associative array, new value is appended to the existing associative array 10

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