Common commands and statements for Shell programming (SCRIPT) and Common commands for shell

Common commands and statements for Shell programming (SCRIPT) and Common commands for shell
Some common Shell programming (SCRIPT) commands and statements can meet general requirements.
Command Parameters received:

• Number of parameters:

$ #

• Parameter value:

Command itself: $0 first parameter: $1 second parameter: $2 ......
Exit command:Exit
Echo command:

• Line feed:

Echo

• Do not wrap after output:

Echo-n "select (y/n )? "

• Use escape characters to output double quotation marks:

Echo "Welcome to \" official server \ "Deployment Tool. "

• The output contains variables:

Echo "project to be deployed: $ project_name"

• Output A string with an escape character:

Echo-e "first \ tsecond"

• Output to file

Append to the end of the file: echo-e $ log_info> deploy. log overwrite the file content: echo-e $ log_info> deploy. log
Printf command: (Echo can be used instead to format the output, which is the same as the printf function in C)

• Output The number of two digits after the decimal point and wrap the line:

Printf "The number is %. 2f. \ n" 100

• Output a string of the specified width:

Left alignment: printf "%-20 s %-15 s % 10.2f \ n" "Stephen" "Liu" 35 right alignment: printf "| % 10s | \ n" hello
Variable:

• Definition:

Profile = "production"

• Usage:

Echo $ profile

• Variable concatenation:

Log_info = "$ log_info, $ target_ip"
Array:

• Definition:

Servers = ("192.168.0.31" "192.168.0.39") projects = ("public" "industry" "logistics" "misc ")

• Obtain the entire array:

$ {Projects [*]}

• Obtain the number of array elements:

$ {# Servers [@]}
If statement (condition judgment also applies to the while statement and for statement ):

• Determine whether a variable (project) is not empty:

If [$ project]; then echo "Variable \" project \ "is null." fi

• Judgment is not equal:

If [$ #-ne 3]; then echo "command line parameters are not 3" fi

• Boolean value judgment:

If ["$ is_ip_correct" = false]; then echo "is invalid ip address, use one of the following ip addresses:" echo $ {servers [*]} exit fi

• Equal string judgment:

If ["$ confirm" = "y"] & ["$ confirm "! = "N"]; do # do something... fi

• Regular Expression judgment

If [[$1 = ~ ^ Public | industry $] & [[$3 = ~ ^ [Yn] $]; then # do something... fi
If [[! $ Deploy_more = ~ [Yn]; then # do something... fi

• Determine whether a file exists:

If [! -F target/$ project. war]; then # do something...
Fi

• Determine whether a directory exists:

If [-d $2/webapps/$1]; then # do something... fi

• Determine the suffix of a file name (string)

Backup_file = "/backup/java_data/$1-$ today. war" backup_file = "/backup/java_data/1_1-1_today.gz"
If ["$ {backup_file ##*.} "=" war "]; then cp $ backup_file $ 1.war elif [" $ {backup_file ##*.} "=" gz "]; then tar zxvf $ backup_file else echo" backup file format incorrect "exit fi
Read Statement (read user input string ):

• Simplest usage: read user input to the variable yes_or_no

Read yes_or_no

• Prompt user to enter y or n

Read-e-p "backup? (y/n )? "-I" y "needbackup (parameter description:-e: I do not know what to use, but if it is removed,-I will become invalid;-p: the subsequent prompt statement; -I: followed by the default input. The last parameter is to save the user input variables .)
Select Statement (prompting you to select one from the list ):

• Modify the default prompt (the default value is "#? "):

PS3 = "select a project :"

• You are prompted to select a value from the array:

Select project in $ {projects [*]}; do if [$ project]; then break fi done
Or add the Exit condition: select target_ip in $ {servers [*]} "Exit (Exit)"; do if ["$ target_ip" = "Exit (Exit)"]; then echo "Thank you! Good-Bye! "Break fi
If [$ target_ip]; then # do something fi done
Case statement:Case $ project in public) project_name = ""; logistics) project_name = ""; misc) project_name = ""; esac
While statement:

• Use the regular expression to determine whether to use:

While [[! $ Needbackup = ~ ^ [Yn] $]; do read-e-p "backup? (y/n )? "-I" y "needbackup done

• Use "..." as the progress bar

Echo-n "waiting for $ port to open ...... "While [! $ Pid_new]; do # sleep 1 pid_new = 'netstat-nlp | grep $ port | awk' {print $7} '| awk-F "/"' {print $1} ''echo- n "... "Done
For statement:

• Traversal:

For ip_t in $ {servers [*]}; do if ["$2" = "$ ip_t"]; then is_ip_correct = true break fidone
Call other programs:

• Use ''and get the output result:

PS3 = "select a branch:" select branch in 'svn list svn: // <svn_host>/java/code/branches '; do if [$ branch]; then svn_dir = "svn: // <svn_host>/java/code/branches/$ branch" project_dir = $ branch break fi done

• Use $ () and obtain the output result:

Today = $ (date + % Y-% m-% d/% H: % M: % S) svn_version = $ (svn info $ svn_dir | grep "Last Changed Rev: "| awk '{print $4 }')

• Call other programs silently (no result is output, that is, the result is output to a null device)

Rm $2/logs/m * $2/logs/l * $2/logs/h * $2/logs/catalina.2015 * &>/dev/null &
Awk (used to slice strings, usually used with grep ):

• Obtain the fourth string separated by spaces:

Svn_version = $ (svn info $ svn_dir | grep "Last Changed Rev:" | awk '{print $4 }')

• Returns the first string separated by a special separator ("/").

Awk-F "/" '{print $1 }'

• Get all processes whose port number is $ port and kill

For pid in 'netstat-nlp | grep $ port | awk' {print $7} '| awk-F "/"' {print $1} ''Do echo "= ============================================================ ========= "echo" cannot close the process normally, port: $ port, kill directly, process Number: $ pid "echo" ============================ Warning ======== ==================== "kill $ piddone
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