Shell Programming and Scripting

Hi I have a simple code that I want to execute.

Code:

out=out.txt
for f in `cat list.txt | head -1`; do
	
	echo $f >> $out
	echo "sleep 5" >> $out
done

cat list.txt | head -1

wget -q -O - 'http://test.com:15100/cgi-bin/search


cat out.txt

wget
sleep 5
-q
sleep 5
-O
sleep 5
-
sleep 5
'http://test.com:15100/cgi-bin/search'
sleep 5

The problem is list.txt contains spaces and they are treated as separator.

My ideal output is of course to show

wget -q -O - 'http://test.com:15100/cgi-bin/search'
sleep 5

Any smart way to do this preferably using less code.

One awk line can do your job

Code:

 awk '{if($1=="wget")print $0"\nsleept 5"}' list.txt > out.txt

Not sure why you need a loop

head -1 list.txt > out.txt
echo sleep 5 >> out.txt

Code:

IFS= read -r f < list.txt
printf "%s\n" "$f" > "$out"

Just to deviate as little as possible from your original,

Code:

head -1 list.txt >>$out   # yes, the cat is completely meaningless
echo sleep 5 >>$out

If you actually need to get the output into backticks, take care to quote properly.

Code:

string_with_spaces="`head -1 list.txt`"

And head is an unnecessary external command. It is much faster to use read to get the first line from a file.

The quotes are unnecessary.

It is not a string with spaces that is being assigned to the variable, it is the output of command substitution, which is not subject to word splitting by the shell.

Granted, the quotes are unnecessary in this context -- I didn't want to go back to the useless for loop just to explain the issue, so I made a rather inexact statement instead. Humor me.

Looks like ohagar already posted an identical suggestion -- sorry, missed that somehow before.

Anyway, I believe there is an option in wget itself to wait a specified number of seconds between retrieving two URLs, so the whole question seems kind of ... intriguing.