shell--to Be Continued

Bash variables

? variable = value

? Reference by: $ variable

[Email protected] desktop]# hi="Hello,and Welcome to $ (hostname). "  Echo  $HIHello, and welcome to localhost.localdomain.[ [Email protected] desktop]#

? &>: Redirect all outputs

? 2>&1: redirect stderr to stdout

? >: Redirected stdout

? 2>: Redirect StdErr

 [[email protected] test]# ll *. sh  *.txt > AAA  ls : Cannot access *.txt:no such file   or directory[[email protected] test]#  cat  Span style= "COLOR: #000000" > AAA -rwxr--r--. 1  root root 158  June 28  06 : 36  test1. sh -rwxrwxrwx. 1  root root 59  June 28  06 : 33  test. sh    

[email protected] test]# ll*.SH*.txt2>BBB-rwxr--r--.1Root root158June -  .: $Test1.SH-rwxrwxrwx.1Root root -June -  .: -Test.SH[email protected] test]#CatBBBls: Cannot access *.txt:no suchfileor directory

 [[email protected "test]# ll  *. sh  *.txt &> ccc[[email protected] test]#  cat   CCC  ls : Cannot access *.txt:no such file   or directory -rwxr--r--. 1  root root 158  June 28  06 : 36  test1. sh -rwxrwxrwx. 1  root root 59  June 28  06 : 33  test. sh  

redirect from file to standard input:

Cat1158: test1. SH 1 root root  : Test.  SH

 [[email protected] test]#  cat  AAA | tr   " a-z   "  " a-z   "-rwxr--r--. 1  root root 158  June 28  06 : 36   TEST1. SH -rwxrwxrwx. 1  root root 59  June 28  06 : 33   TEST. SH  

TR ' A- z ' ' A- z '  <AAA1158:  TEST1. SH1 root root  : TEST. Sh

For statement:

[Email protected] test]#Cat  for.SH #!/bin/Bash forNAMEinchJoe Jak Sky DoMESSAGE='Hello World'   EchoThe He name is $NAME."$NAME say $MESSAGE!" Done[email protected] test]#./ for.SHHe name is Joe. Joe Say hello world!The He name is Jak. Jak Say hello world!He name is sky. Sky Say hello world![email protected] test]#

[email protected] test]# cat for1.sh
#!/bin/bash
For num in $ (SEQ 1 6)
Do
Echo $num
Done
[Email protected] test]#./for1.sh
1
2
3
4
5
6
[Email protected] test]#

[Email protected] test]#Cat if.SH #!/bin/Bashif Ping-c1-w2128.0.0.1&>/dev/NULL; Then    EchoNetwork SERVICE is up!elif grepNetwork/weihu.txt &>/dev/NULL; Then    EchoNetwork Service isinchMaintenance!Else   EchoStation was down!fi[email protected] test]#

shell--to Be Continued