So, I simplified this code. Every time it runs, else or $msg4 is always executed. How do I change it so it only does else if the $nick part doesn't match?
if [ "$who" = "$nick1" ]
then echo $msg1
fi
if [ "$who" = "$nick2" ]
then echo $msg2
fi
if [ "$who" = "$nick3" ]
then echo $msg3
else $msg4
fi
Here you can read how Bash if statements work: https://www.gnu.org/software/bash/manual/html_node/Conditional-Constructs.html#Conditional-Constructs
There you can see there is an elif which you should use to chain multiple if - else things together so that the final else is only executed if none of the if statements match. Result:
if [ "$who" = "$nick1" ]
then
echo $msg1
elif [ "$who" = "$nick2" ]
then
echo $msg2
elif [ "$who" = "$nick3" ]
then
echo $msg3
else
echo $msg4
fi
You can also write the then on the same line as if if you add a ; before then:
if [ "$who" = "$nick1" ]; then
echo $msg1
elif [ "$who" = "$nick2" ]; then
echo $msg2
elif [ "$who" = "$nick3" ]; then
echo $msg3
else
echo $msg4
fi
This is often easier to read.
Use case .. esac
case "$who" in
"$nick1") echo "$msg1";;
"$nick2") echo "$msg2";;
"$nick3") echo "$msg3";;
*) echo "$msg4";;
esac
Related
I would like to write in one line this:
if [$SERVICESTATEID$ -eq 2]; then echo "CRITICAL"; else echo "OK"; fi
So to do a test in my shell I did:
if [2 -eq 3]; then echo "CRITICAL"; else echo "OK"; fi
The result is
-bash: [2: command not found
OK
So it doesn't work.
Space -- the final frontier. This works:
if [ $SERVICESTATEID -eq 2 ]; then echo "CRITICAL"; else echo "OK"; fi
Note spaces after [ and before ] -- [ is a command name! And I removed an extra $ at the end of $SERVICESTATEID.
An alternative is to spell out test. Then you don't need the final ], which is what I prefer:
if test $SERVICESTATEID -eq 2; then echo "CRITICAL"; else echo "OK"; fi
Write like this, space is required before and after [ and ] in shell
if [ 2 -eq 3 ]; then echo "CRITICAL"; else echo "OK"; fi
Shorter format.
( [ 2 -eq 3 ] && echo "CRITICAL" ) || echo "OK"
Regex pattern type numbers : 10,12.1,+3.33,-1,0004,-48.9
Oneliner attacks again!
( [ `echo $number 2>/dev/null | grep -E "^[ ]*(\+|\-){0,1}[0-9]+(\.[0-9]+)?$"` ] && echo "NUMBER" ) || echo "NOT NUMBER"
Hello here is my primary script. The test2.sh is just an echo "it worked"
what happens when I try and call from the original loop, it gets to the correct file then echo's infinite "it worked" where it should just be doing it once.
Any idea why? I really want to have another loop called outside of the main script that won't interfere, but still learning bash =P
#!/bin/bash
number=1
while true
do
if [ "$number" -eq "1" ]; then
echo "hello 1!"
elif [ "$number" -eq "2" ]; then
echo "hello 2!"
elif [ "$number" -eq "3" ]; then
echo "hello 3!"
elif [ "$number" -eq "4" ]; then
./test2.sh & continue
fi
sleep 5
((number++))
echo $number
done
first observation & is not a logical operator, & runs the precedding command in the background. Use && for logical operations.
what you need is a break keyword not a continue keyword . If you use the break keyword, the loop will stop executing. The continue keyword only rexecutes the loop , and since number is 4 , this branch of code will always run elif [ "$number" -eq "4" ]; then
working code
#!/bin/bash
number=1
while true
do
if [ "$number" -eq "1" ]; then
echo "hello 1!"
elif [ "$number" -eq "2" ]; then
echo "hello 2!"
elif [ "$number" -eq "3" ]; then
echo "hello 3!"
elif [ "$number" -eq "4" ]; then
./test2.sh && break
fi
sleep 5
((number++))
echo $number
done
or you can do this
for number in {1..4};do
(( number == 4 )) && ./test2.sh || echo "$number"
sleep 5
done
I would like to write in one line this:
if [$SERVICESTATEID$ -eq 2]; then echo "CRITICAL"; else echo "OK"; fi
So to do a test in my shell I did:
if [2 -eq 3]; then echo "CRITICAL"; else echo "OK"; fi
The result is
-bash: [2: command not found
OK
So it doesn't work.
Space -- the final frontier. This works:
if [ $SERVICESTATEID -eq 2 ]; then echo "CRITICAL"; else echo "OK"; fi
Note spaces after [ and before ] -- [ is a command name! And I removed an extra $ at the end of $SERVICESTATEID.
An alternative is to spell out test. Then you don't need the final ], which is what I prefer:
if test $SERVICESTATEID -eq 2; then echo "CRITICAL"; else echo "OK"; fi
Write like this, space is required before and after [ and ] in shell
if [ 2 -eq 3 ]; then echo "CRITICAL"; else echo "OK"; fi
Shorter format.
( [ 2 -eq 3 ] && echo "CRITICAL" ) || echo "OK"
Regex pattern type numbers : 10,12.1,+3.33,-1,0004,-48.9
Oneliner attacks again!
( [ `echo $number 2>/dev/null | grep -E "^[ ]*(\+|\-){0,1}[0-9]+(\.[0-9]+)?$"` ] && echo "NUMBER" ) || echo "NOT NUMBER"
I need a logic to implement the following logic in unix
if ( $a !="xyz" || $d !="abc" ) && ( $b= $c))
then
echo "YES WORKING"
fi
I tried below code not working
if [ [ [ $a != "xyz" ] -o [ $d != "abc" ] ] -a [ "$b" = "$c" ] ]
then
echo "YES WORKING"
fi
getting error as
:[ :] unexpected operator/operand
You can do something like this:
[ $a != "xyz" -o $d != "abc" ] && [ "$b" = "$c" ] && echo "YES WORKING"
Your logic should work easy in shells supporting [[ ]]:
if [[ ($a != "xyz" || $d != "abc") && $b = "$c" ]]; then
echo "YES WORKING"
fi
Although there's a way for those that doesn't:
if ([ ! "$a" = "xyz" ] || [ ! "$d" = "abc" ]) && [ "$b" = "$c" ]; then
echo "YES WORKING"
fi
But that's still inefficient since you'd be summoning subshells, so use { } but the syntax is a little ugly:
if { [ ! "$a" = "xyz" ] || [ ! "$d" = "abc" ]; } && [ "$b" = "$c" ]; then
echo "YES WORKING"
fi
#!/bin/bash
if [$# -ne 1];
then
echo "/root/script.sh a|b"
else if [$1 ='a'];
then
echo "b"
else if [$1 ='b']; then
echo "a"
else
echo "/root/script.sh a|b"
fi
I'm getting below error while run above script in Linux.
bar.sh: line 2: [: S#: integer expression expected
a
Could you please help to remove this error?
if [$# -ne 1];
[ and ] requires spacing. Example:
if [ $# -ne 1 ];
And else if should be elif
#!/bin/bash
if [ "$#" -ne 1 ];
then
echo "/root/script.sh a|b"
elif [ "$1" ='a' ];
then
echo "b"
elif [ "$1" ='b' ]; then
echo "a"
else
echo "/root/script.sh a|b"
fi
Do not forget to quote variables. It is not every time necessary, but recommended.
Question: Why do i have -1?
Bash doesn't allow else if. Instead, use elif.
Also, you need spacing within your [...] expression.
#!/bin/bash
if [ $# -ne 1 ];
then
echo "/root/script.sh a|b"
elif [ $1 ='a' ];
then
echo "b"
elif [ $1 ='b' ]; then
echo "a"
else
echo "/root/script.sh a|b"
fi