shell script: if statement

Question

I'm following the tutorial here: http://bash.cyberciti.biz/guide/If..else..fi#Number_Testing_Script

My script looks like:

lines=`wc -l $var/customize/script.php`
if test $lines -le 10
then
    echo "script has less than 10 lines"
else
    echo "script has more than 10 lines"
fi

but my output looks like:

./boot.sh: line 33: test: too many arguments
script has more than 10 lines

Why does it say I have too many arguments? I fail to see how my script is different from the one in the tutorial.

Did you the first line #!/bin/bash in your script? Also are you running the script in bash shell or ksh? — Raghuram
– Raghuram, Commented Jun 12, 2012 at 9:00

kev · Accepted Answer · 2012-06-12 09:05:31Z

10

wc -l file command will print two words. Try this:

lines=`wc -l file | awk '{print $1}'`

To debug a bash script (boot.sh), you can:

$ bash -x ./boot.sh

It'll print every line executed.

edited Jun 12, 2012 at 9:05

answered Jun 12, 2012 at 8:59

kev

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4 Comments

mvds Over a year ago

@KevinDuke you should add a line echo lines contains $lines so you can see what's going on...

Karthick S Over a year ago

One way to help you in these cases is by using the -x option: "sh -x ./script_name" This prints out the script with the variable values substituted.

ghoti Over a year ago

wc -l < file will return only one word, though it needs to be trimmed.

ghoti Over a year ago

awk 'END{print NR}' file will also count lines.

mvds · Accepted Answer · 2012-06-12 15:17:06Z

8

wc -l file

outputs

1234 file

use

lines=`wc -l < file`

to get just the number of lines. Also, some people prefer this notation instead of backticks:

lines=$(wc -l < file)

Also, since we don't know if $var contains spaces, and if the file exists:

fn="$var/customize/script.php"
if test ! -f "$fn"
then
    echo file not found: $fn
elif test $(wc -l < "$fn") -le 10
then
    echo less than 11 lines
else
    echo more than 10 lines
fi

edited Jun 12, 2012 at 15:17

answered Jun 12, 2012 at 9:00

mvds

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1 Comment

William Pursell Over a year ago

This will produce unexpected output if the script has permission issues, or some other error occurs. Probably better to just run wc and abort if it fails, allowing wc to print an appropriate error message (which belongs on stderr). For example: a=$( wc -l < "$fn" ) || exit 1; if test "$a" -le 10; then ...

jpaugh · Accepted Answer · 2012-06-13 02:17:11Z

1

Also, you should use

if [[ $lines -gt 10 ]]; then
    something
else
  something
fi

test condition is really outdated, and so is it's immediate successor, [ condition ], mainly because you have to be really careful with those forms. For example, you must quote any $var you pass to test or [ ], and there are other details that get hairy. (tests are treated in every way as any other command). Check out this article for some details.

edited Jun 13, 2012 at 2:17

answered Jun 12, 2012 at 9:16

jpaugh

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2 Comments

Dennis Williamson Over a year ago

In Bash, for integer comparisons, you should use if (( lines < 10 )). The comparison you are showing is a lexical comparison which will fail for $lines with a value of 2, for example.

William Pursell Over a year ago

test and [ are not outdated, just highly abused. But they are much more portable than [[ and ((.

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