Legacy ImageMagick Discussions Archive

Hello,

I use LINUX system and something really strange occured.

When I used the command to convert a tif image into a pdf image (notice that has spaces in the names of images):

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$ convert "/tmp/image 16832.tif" "/tmp/image 16833.tif" "/tmp/test alpha.pdf"

thats ok!

But when I used variables (cause I wanna put this code into a script):

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$ image="\"/tmp/image 16832.tif\" \"/tmp/image 16833.tif\""
$ path="\"/tmp/test alpha.pdf\""
$ convert $image $path

returned the error:

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convert: unable to open image `"/tmp/image':No such file or directory @ blob.c/OpenBlob/2480.
convert: unable to open image `16832.tif"': No such file or directory @ blob.c/OpenBlob/2480.
convert: unable to open image `"/tmp/image': No such file or directory @ blob.c/OpenBlob/2480.
convert: unable to open image `16833.tif"': No such file or directory @ blob.c/OpenBlob/2480.
convert: unable to open image `"/tmp/test': No such file or directory @ blob.c/OpenBlob/2480.
convert: missing an image filename `alpha.pdf"' @ convert.c/ConvertImageCommand/2838.

So I try to see the mistake:

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$ echo convert $image $path
convert "/tmp/image 16832.tif" "/tmp/image 16833.tif" "/tmp/test alpha.pdf"

(equal to the first code ????)

I don't know where is the problem, I already used similar code with another commands in LINUX, then I tried to search what's wrong and I just find windows and mac similiar problems, but they don't help me.

Thanks for reading !

$ image="\"/tmp/image 16832.tif\" \"/tmp/image 16833.tif\""

I don't think you can nest quotes with spaces in filenames that way, but I am not an expert

I think it still resolves to the same as

image="tmp/image 16832.tif tmp/image 16833.tif"

which still has the spaces.

Spaces in file or directory names are always messy.

The following works for me, in Ubuntu (bash):

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NAME3=$'three\x20logo.png'
NAME4=$'four logo.png'
convert logo: "$NAME3"
convert logo: "$NAME4"

creating files named "three logo.png" and "four logo.png".

snibgo:

I think he wants to have multiple inputs to convert and generate a multipage pdf, rather than multiple converts. Of course one can do a loop over each input and successively convert and add them to a multipage pdf.

I figured out a way to do it.

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echo convert "$image" "$path" >tmp
chmod tmp 755
bash tmp

Pete

I like that batch file.

Multiple inputs, each with a space, expressed as a variable? How about with arrays:

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#!/bin/bash
NAME3=$'three\x20log.png'
NAME4=$'four log.png'
convert logo: "$NAME3"
convert logo: -transparent White -flip "$NAME4"

NAMEARR[0]=$'three\x20log.png'
NAMEARR[1]=$'four log.png'

# The next three converts do the same thing:
#
convert -verbose "${NAMEARR[@]}" -composite out.png
convert -verbose logo: \( logo: -transparent White -flip \) -composite out2.png
convert "three log.png" "four log.png" -composite out3.png

fmw42
image="tmp/image 16832.tif tmp/image 16833.tif" -> don't work

snibgo
fmw42 has reason, I wanna multiple inputs to convert and generate a multipage pdf. I can make a loop and solve quickly this problem, but I wanna to understand why this strange thing is happen.

el_supremo
your code works, but I would like to understand why? I mean, whats the difference between put the code direct into bash or make this through script? Or whats the difference between put the string direct or make this through variables (like i did before) ?

snibgo
I am not used to deal with arrays cause it doesn't works in some shells, but its a idea, thanks!!

your code works, but I would like to understand why?

The shell only makes one pass through the command line breaking it up into arguments.

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convert "/tmp/image 16832.tif" "/tmp/image 16833.tif" "/tmp/test alpha.pdf"

When it reads the above command line, it sees the first quote and then stores everything up to the second quote as the first argument. Then it sees the next quote and so on, resulting in three arguments to the convert command.

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$ image="\"/tmp/image 16832.tif\" \"/tmp/image 16833.tif\""
$ path="\"/tmp/test alpha.pdf\""
$ convert $image $path

When it processes the third line above, the line does not contain any quotes. So the shell does the variable substitution and breaks the resulting string into arguments at each space which is why you get six error messages from convert. If you had used this command:

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$ convert "$image" "$path"

The interpretation of the output argument would now be what you intended because $path would have been expanded into one string. But the $image would also have been passed as one string so that convert would see only two arguments, the $image string and the $path string.
The basic problem here is that the $image string contains two "types" of space. The first and third spaces are just parts of a filename, but the second one is intended to be interpreted as an argument separator. But the shell doesn't "know" that and in order for it to interpret this properly it would have to make two passes through the argument string. The only way to make that happen (that I know of) is to run it through another shell.

Pete

rogeriobrasiliense wrote:But when I used variables (cause I wanna put this code into a script):
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$ image="\"/tmp/image 16832.tif\" \"/tmp/image 16833.tif\""
$ path="\"/tmp/test alpha.pdf\""
$ convert $image $path

You have hit the first big hurdle people have when creating shell scripts. And yes this is all shell scripting and NOTHING to do with ImageMagick itself.

I have been creating complex shell script programming for 22 years now, so I should know a thing or two about this

First of all as the variable was NOT in quotes, the shell expanded the string, then parsed the command breaking it up into spaces.

The next thing you try is to quote the variable. Something you should generally always do in a shell script.

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convert "$image" "$path"

However that results in

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  convert "\"/tmp/image 16832.tif\" \"/tmp/image 16833.tif\""  "\"/tmp/test alpha.pdf\""

Which is only TWO arguments not three quoted arguments.

The TRICK, as some people have attempted to do by 'echo'ing the command to a script and executing that, is to have the shell 'parse' the command twice! That is done using a special shell command called "eval"

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  eval "convert $image $path"

That will be parsed once by shell substituting all the strings, to produce...

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convert "/tmp/image 16832.tif"  "/tmp/image 16833.tif"  "/tmp/test alpha.pdf"

Which will then me parsed into arguments and execututed JUST AS YOU WANT.

The more typical example of "eval" is 'variable indirection'

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a="THE DATA"
b=a
eval echo \"\$$b\"

The eval parses the echo command, removing the backslash from the first $ sign, and substituting the contents of $b, so that it then generates

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echo "$a"

Which when executed outputs...

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THE DATA

I have even used this to generate a very very very complex data structure (hash tables and trees) in shell scripts!!!! It does work, though the backslashes of eval's of eval's can become a real nightmare!

I suggest you google for many BASH FAQ guides that are around, which will probably explain "eval" much more fully.

Fred I am sure you can find and reproduce a long list of them

el_supremo wrote:I figured out a way to do it.
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echo convert "$image" "$path" >tmp
chmod tmp 755
bash tmp
Pete

Whcih is basically an 'eval' but using a sub-shell (executing a temporary file). This is something that is common practice in DOS scripting.

Unfortunately you can not easy assign to variables within a sub-shell like this, and any variable assignment will be in the sub-shell and not in the main shell. That is variable assignments get lost.

You get a similar problem when piping data to a compound shell command like 'for' 'while' or 'if'. And it can be a real problem to figure out a solutions
Eval does not have that problem...

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a="DATA"
b=a
eval c=\"\$$b\"
echo "$c"

the result is that c was assigned the string "DATA". Try doing that in a executed tmp and you will fail (though their are solutions for that too).

Legacy ImageMagick Discussions Archive

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Re: Problem convert tif to pdf " @ blob.c/OpenBlob/2480."

Re: Problem convert tif to pdf " @ blob.c/OpenBlob/2480."

Re: Problem convert tif to pdf " @ blob.c/OpenBlob/2480."

Re: Problem convert tif to pdf " @ blob.c/OpenBlob/2480."

Re: Problem convert tif to pdf " @ blob.c/OpenBlob/2480."

Re: Problem convert tif to pdf " @ blob.c/OpenBlob/2480."

Re: Problem convert tif to pdf " @ blob.c/OpenBlob/2480."