Error [: -lt: unary operator expected in shell script Linux
I get error [: -lt: unary operator expected after run below script, anyone can share ideas?
temp=0
while [ $temp -lt 25 ]
do
sleep 1
echo "running.."
if [ $temp -eq 5 ]
then
top -bc -d 5 -n 1|sed -n '7,8p'|awk '{print $1,$9}'>>out.txt
temp=`expr $temp +1`
break
elif [ $temp -eq 20 ]
then
top -bc -d 5 -n 1|sed -n '7,8p'|awk '{print $1,$9}'>>out.txt
temp=`expr $temp +1`
else
temp=`expr $temp +1`
fi
done
linux shell-script test
edited 3 hours ago
Jeff Schaller
39.3k1054125
asked 3 hours ago
Shi Jie TioShi Jie Tio
1163
New contributor
Shi Jie Tio is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I get error [: -lt: unary operator expected after run below script, anyone can share ideas?
temp=0
while [ $temp -lt 25 ]
do
sleep 1
echo "running.."
if [ $temp -eq 5 ]
then
top -bc -d 5 -n 1|sed -n '7,8p'|awk '{print $1,$9}'>>out.txt
temp=`expr $temp +1`
break
elif [ $temp -eq 20 ]
then
top -bc -d 5 -n 1|sed -n '7,8p'|awk '{print $1,$9}'>>out.txt
temp=`expr $temp +1`
else
temp=`expr $temp +1`
fi
done
linux shell-script test
edited 3 hours ago
Jeff Schaller
39.3k1054125
asked 3 hours ago
Shi Jie TioShi Jie Tio
1163
New contributor
Shi Jie Tio is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
Do you also get errors fromexpr?
– Michael Homer
3 hours ago
no error shown on expr
– Shi Jie Tio
3 hours ago
Use More Quotes™
– l0b0
3 hours ago
add a comment |
I get error [: -lt: unary operator expected after run below script, anyone can share ideas?
temp=0
while [ $temp -lt 25 ]
do
sleep 1
echo "running.."
if [ $temp -eq 5 ]
then
top -bc -d 5 -n 1|sed -n '7,8p'|awk '{print $1,$9}'>>out.txt
temp=`expr $temp +1`
break
elif [ $temp -eq 20 ]
then
top -bc -d 5 -n 1|sed -n '7,8p'|awk '{print $1,$9}'>>out.txt
temp=`expr $temp +1`
else
temp=`expr $temp +1`
fi
done
linux shell-script test
edited 3 hours ago
Jeff Schaller
39.3k1054125
asked 3 hours ago
Shi Jie TioShi Jie Tio
1163
New contributor
Shi Jie Tio is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I get error [: -lt: unary operator expected after run below script, anyone can share ideas?
temp=0
while [ $temp -lt 25 ]
do
sleep 1
echo "running.."
if [ $temp -eq 5 ]
then
top -bc -d 5 -n 1|sed -n '7,8p'|awk '{print $1,$9}'>>out.txt
temp=`expr $temp +1`
break
elif [ $temp -eq 20 ]
then
top -bc -d 5 -n 1|sed -n '7,8p'|awk '{print $1,$9}'>>out.txt
temp=`expr $temp +1`
else
temp=`expr $temp +1`
fi
done
linux shell-script test
linux shell-script test
edited 3 hours ago
Jeff Schaller
39.3k1054125
asked 3 hours ago
Shi Jie TioShi Jie Tio
1163
New contributor
Shi Jie Tio is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 3 hours ago
Jeff Schaller
39.3k1054125
asked 3 hours ago
Shi Jie TioShi Jie Tio
1163
New contributor
Shi Jie Tio is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 3 hours ago
Jeff Schaller
39.3k1054125
edited 3 hours ago
Jeff Schaller
39.3k1054125
edited 3 hours ago
Jeff Schaller
39.3k1054125
39.3k1054125
asked 3 hours ago
Shi Jie TioShi Jie Tio
1163
New contributor
Shi Jie Tio is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 3 hours ago
Shi Jie TioShi Jie Tio
1163
asked 3 hours ago
Shi Jie TioShi Jie Tio
1163
1163
New contributor
Shi Jie Tio is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Shi Jie Tio is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Shi Jie Tio is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
Do you also get errors fromexpr?
– Michael Homer
3 hours ago
no error shown on expr
– Shi Jie Tio
3 hours ago
Use More Quotes™
– l0b0
3 hours ago
add a comment |
1
Do you also get errors fromexpr?
– Michael Homer
3 hours ago
no error shown on expr
– Shi Jie Tio
3 hours ago
Use More Quotes™
– l0b0
3 hours ago
1
1
Do you also get errors from
expr?– Michael Homer
3 hours ago
Do you also get errors from
expr?– Michael Homer
3 hours ago
no error shown on expr
– Shi Jie Tio
3 hours ago
no error shown on expr
– Shi Jie Tio
3 hours ago
Use More Quotes™
– l0b0
3 hours ago
Use More Quotes™
– l0b0
3 hours ago
add a comment |
1 Answer
1
active
oldest
votes
Try changing all the +1s after the exprs to + 1.
Without the space expr will return an error and $temp will be empty. If $temp is empty, then the -lt will be comparing a blank space to a number, which is why the error appears. Here's a one liner that reproduces the problem:
t=0;t=`expr $t +1`;[ $t -lt 25 ]
Output (to STDERR):
expr: syntax error
bash: [: -lt: unary operator expected
Better yet, change all code that uses the external util expr to use the shell's own internal arithmetic expansion. So code like this:
temp=`expr $temp +1`
...should be changed to:
temp=$(($temp + 1))
answered 3 hours ago
agcagc
4,50311036
add a comment |
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1 Answer
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1 Answer
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active
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votes
Try changing all the +1s after the exprs to + 1.
Without the space expr will return an error and $temp will be empty. If $temp is empty, then the -lt will be comparing a blank space to a number, which is why the error appears. Here's a one liner that reproduces the problem:
t=0;t=`expr $t +1`;[ $t -lt 25 ]
Output (to STDERR):
expr: syntax error
bash: [: -lt: unary operator expected
Better yet, change all code that uses the external util expr to use the shell's own internal arithmetic expansion. So code like this:
temp=`expr $temp +1`
...should be changed to:
temp=$(($temp + 1))
answered 3 hours ago
agcagc
4,50311036
add a comment |
Try changing all the +1s after the exprs to + 1.
Without the space expr will return an error and $temp will be empty. If $temp is empty, then the -lt will be comparing a blank space to a number, which is why the error appears. Here's a one liner that reproduces the problem:
t=0;t=`expr $t +1`;[ $t -lt 25 ]
Output (to STDERR):
expr: syntax error
bash: [: -lt: unary operator expected
Better yet, change all code that uses the external util expr to use the shell's own internal arithmetic expansion. So code like this:
temp=`expr $temp +1`
...should be changed to:
temp=$(($temp + 1))
answered 3 hours ago
agcagc
4,50311036
add a comment |
Try changing all the +1s after the exprs to + 1.
Without the space expr will return an error and $temp will be empty. If $temp is empty, then the -lt will be comparing a blank space to a number, which is why the error appears. Here's a one liner that reproduces the problem:
t=0;t=`expr $t +1`;[ $t -lt 25 ]
Output (to STDERR):
expr: syntax error
bash: [: -lt: unary operator expected
Better yet, change all code that uses the external util expr to use the shell's own internal arithmetic expansion. So code like this:
temp=`expr $temp +1`
...should be changed to:
temp=$(($temp + 1))
answered 3 hours ago
agcagc
4,50311036
Try changing all the +1s after the exprs to + 1.
Without the space expr will return an error and $temp will be empty. If $temp is empty, then the -lt will be comparing a blank space to a number, which is why the error appears. Here's a one liner that reproduces the problem:
t=0;t=`expr $t +1`;[ $t -lt 25 ]
Output (to STDERR):
expr: syntax error
bash: [: -lt: unary operator expected
Better yet, change all code that uses the external util expr to use the shell's own internal arithmetic expansion. So code like this:
temp=`expr $temp +1`
...should be changed to:
temp=$(($temp + 1))
answered 3 hours ago
agcagc
4,50311036
edited 3 hours ago
answered 3 hours ago
agcagc
4,50311036
answered 3 hours ago
agcagc
4,50311036
answered 3 hours ago
agcagc
4,50311036
4,50311036
add a comment |
add a comment |
Shi Jie Tio is a new contributor. Be nice, and check out our Code of Conduct.
Shi Jie Tio is a new contributor. Be nice, and check out our Code of Conduct.
Shi Jie Tio is a new contributor. Be nice, and check out our Code of Conduct.
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1
Do you also get errors from
expr?– Michael Homer
3 hours ago
no error shown on expr
– Shi Jie Tio
3 hours ago
Use More Quotes™
– l0b0
3 hours ago