学习shell(5)
2Ty/z/J.w${"s3R0 控制流结构
?\h!d#T*m4Q @#o0P*E"Gj,T,X4J4Q01.if 语句Linux宝库w-uF8Oq;i
+P3Aw| }C1sg4~1{0格式用法如下:
|#OCs#@.V#X8c0 Linux宝库$D/U8@/l|!~C cif 条件1
-o4i.c V.U0 Linux宝库 WI!Fj F)P TXL4nthen 命令1Linux宝库 mZ^%h&HInl5z@,{
Linux宝库C;Y,A2x'p\OKelif 条件2Linux宝库fk(o:p8P%iA:~
Linux宝库5O9T^Vv[#\then 命令2Linux宝库f b/{#M#b9k4I+A7z
.N\QFI0else 命令3Linux宝库0PV,ev }
Linux宝库2Uh} Hu8V o*a$wfi //必须以fi 结束完成
A8@Z'F.x"l\0 Linux宝库^O/} FQz PQAuE四个简单的例子:Linux宝库1fD)n5L!hZ ~
_.LY-pS0#!/bin/bashLinux宝库-\3u gV0_DIH,bg
d3Bh"zlS0#iftest1
K\pIn-w0 Linux宝库wZC ][if [ "10" -lt "12"]Linux宝库PygHc FC k.q-O
Linux宝库mNu?2o)x@dthenLinux宝库g]WbGC
Linux宝库0uv&o0q0B8jiecho "Yes, 10 is less than 12"
7s1E*OCl}.Sq+L0e^E9FtfE0fi
9m@6F8k,mA0 Linux宝库L#W9Ji]3F&E#Q#!/bin/bash
*S8Q m F&X)j0 Linux宝库7c3x;U)VF(v^hgF#iftest2Linux宝库+c#|j W4P(u4O
&_s9Ec2^3eqf6W0echo -n "Enter your name:"
h? cjQ*f#p|)V0 Linux宝库${X!tE#~5Cread name
)e&Pg,g8]^D0 Linux宝库$G%q9Eg3Eif ["$name" == "" ]; then
g1c2x;C.]/YP-r0 Linux宝库9`"R$Si r5\Yaecho "You did not enter any information"
%ALDl5@O9y,V4g0 Linux宝库Vn'|+q'\Welse
st.R-eN%nh&n0a"@4lsF9o h7dHNm0echo "You Name is ${name}"
;[ e p)B5]n!W"C0y0Z KU ]M5ck0fiLinux宝库I k5UDdde
Linux宝库2G)M/_!{v-z#!/bin/bash
BS"B.X$Q0 Linux宝库@4}%cB1bB1{'o#ifcpLinux宝库Q X3gD mLP%b7EO3YK
Linux宝库"Q-H!o'}4vA(v!Rif cp myfile.bak myfile; then
xp5G,hr!]1S,A#qJ0 Linux宝库vp,U]8z G`b+A Recho "good copy"Linux宝库M)_bTN5Z#B"pk0d
1A [4B,VS ^P0else
1NMx1?r s6@V05[L;NJ2J g,R@$bqv0echo "'basename $0':error could not copy the file" >&2Linux宝库hV!co_A*E
`m b(z}/Z0fiLinux宝库 ^L4YK&b LU h%Quf?
Linux宝库W}U$e,A&p