Conditional judgment in shell programming (Shell 05)

Conditional judgment in shell programming
Conditions
If-then
Case

If-then
Single condition
if command
Then
Commands
Fi
When the command return code is 0 o'clock, the condition is set

if.sh

#! /bin/Bashif Date Then        Echo "command EXEC"fiifdate123 Then        Echo "Command EXEC1"fiEcho "Out if"[[Email protected]SH]# ./if.SHSaturday, October 29, 2016Ten: the: -Edtcommand exec./if.SH: Line8: Date123:command not foundoutif

Full Coverage

if command
Then
Commands
Else
Commands
Fi

if.sh

#! /bin/BashifDate1 Then        Echo "Command"        Echo "OK"Else        Echo "Commond1"        Echo "fail"fi[[Email protected]SH]# ./if.SH./if.SH: Line2: Date1:command not Foundcommond1fail

Conditional nesting

If Command1
Then
Commands
If Command2
Then
Commands
Fi
Commands
Fi

Multi-criteria
If Command1
Then
Commands
Elif Command2
Then
Commands
Else
Commands
Fi

Test command:
The first form of
if test condition
Then
commands
fi
The second form of
Brackets []:
if [condition]
Then
commands
fi
Compound condition judgment
[Condition1] && [Condition2]
[Condition1] | | [Condition2]

Three types of conditions
Numerical comparison
string comparison
File comparison
if.sh

Echoplese input a numread numif[$num-GTTen ] Then        Echo "The num>10"fiif[$num-ltTen] && [$num-gt5 ] Then        Echo "The 5<num<10"fi

[[Email protected]SH]# ./if.SHplese input a num OneThe num>Ten

Cond

Conditional judgment in shell programming (Shell 05)