Shell if judgment

#!/bin/sh

/ETC/INIT.D/SNMPD start && >/dev/null

Pid= '/ETC/INIT.D/SNMPD status| grep pid ' # '/etc/init.d/mysqld status| grep "not running" to see if the status of the service is healthy with the status state

If ["$pid" = = ""]; Then #判断grep的关键词是否为空

echo "SNMP error";

Else

echo "SNMP is OK";

Fi

#mysql进程是否存在

#!/bin/sh

Pid= '/etc/init.d/mysqld status| grep "Not Running" '

If ["$pid" = = ""]; Then

echo "MySQL OK";

Else

echo "$pid"

Service mysqld Start

UNIX Shell comparison character notation:

• -eq    equals

• -ne    not equals

• -gt    greater than

• -lt    less than

• -le    is less than or equal to

• -ge   is greater than or equal to

• -z    empty string

• =     two words typeface etc.

• !=    two characters are not equal to

• -n    non-empty string

Summarize:

Document comparison operators
-e filename If filename exists, true [-e/var/log/syslog]
-d filename If filename is a directory, then true [-d/tmp/mydir]
-F filename True if filename is a regular document [-f/usr/bin/grep]
-L filename True if filename is a symbolic link [-l/usr/bin/grep]
-r filename If filename is readable, true [-r/var/log/syslog]
-W filename if filename is writable, true [-w/var/mytmp.txt]
-X filename is true if filename is executable [-l/usr/bin/grep]
Filename1-nt filename2 if filename1 than filename2 new, then true [/tmp/install/etc/services-nt/etc/services]
Filename1-ot filename2 if filename1 than filename2 old, then true [/boot/bzimage-ot Arch/i386/boot/bzimage]
String comparison operators (note the use of quotation marks, which is a good way to prevent whitespace from disturbing the code)
-Z string true [-Z ' $myvar] if string length is zero
-N String if string length is nonzero, true [-n ' $myvar ']
string1= string2 if string1 and string2 are the same, then true ["$myvar" = "One of the three"]
string1!= string2 if string1 and string2 are different, then true ["$myvar"! = "one of the three"]
Arithmetic comparison operators
Num1-eq num2 equals [3-eq $mynum]
Num1-ne num2 Not equal to [3-ne $mynum]
Num1-lt num2 less than [3-lt $mynum]
Num1-le num2 less than or equal to [3-le $mynum]
NUM1-GT num2 greater than [3-GT $mynum]
Num1-ge num2 greater than or equal to [3-ge $mynum]

This article from "Ren Long" blog, reproduced please contact the author!

Shell if judgment