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Old 09-19-2007
lumdev lumdev is offline
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For loop statement - catch error
I'm having a question about for loops. (bash)

I have the following for example:

for file in `ls *.txt`
do
read file ...
done

Now when there is a file present there is no problem, now when there is no file present I get the following output in my standard mail box : "No such file or directory" Script is executed via crontab.

Now I want to catch the above error so I don't get it in my mail any more, but I have no idea how to do this.

I can make an if statement first "if [ -f *.txt ] ...", but there must be a better solution.

Thx.
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Old 09-19-2007
ajcannon ajcannon is offline
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if
I think the use of the 'if' statement is a perfectly reasonable solution. You need some kind if conditional statement to determine whether or not your file exists and an 'if' would be OK
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Old 09-19-2007
porter porter is offline Forum Advisor  
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Quote:
Originally Posted by lumdev View Post
I can make an if statement first "if [ -f *.txt ] ...", but there must be a better solution.
Check for the actual file in the loop


Code:
  for file in *.txt
  do
     if test -f $file
     then
        read file ...
     fi
  done
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Old 09-19-2007
cfajohnson's Avatar
cfajohnson cfajohnson is offline Forum Advisor  
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Location: Toronto, Canada
Posts: 2,378
Quote:
Originally Posted by lumdev View Post
I'm having a question about for loops. (bash)

I have the following for example:

for file in `ls *.txt`

That is not the way to loop through files. Not only is ls unnecessary, it will break your script if any filenames contain spaces or other pathological characters. Use the wildcard directly:


Code:
for file in *.txt

Quote:
do
read file ...
done

Now when there is a file present there is no problem, now when there is no file present I get the following output in my standard mail box : "No such file or directory" Script is executed via crontab.

Now I want to catch the above error so I don't get it in my mail any more, but I have no idea how to do this.

I can make an if statement first "if [ -f *.txt ] ...", but there must be a better solution.

No, you cannot do that; it will fail if there is more than one .txt file.

You can use a function:


Code:
is_file() {
   test -f "$1"
}

is_file *.txt &&
 for file in *.txt
 do
   ...
 done

The safest way is to check each file:


Code:
for file in *.txt
do
  [ -f "$file" ] || continue
  ...
done
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Old 09-20-2007
lumdev lumdev is offline
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Join Date: Sep 2006
Location: Belgium
Posts: 6
Thx for the answers.

I used the solution with the function, now I don't get any "No such file or directory" output anymore.

Thx for the help cfajohnson.
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