ksh quote or no quote whitespace madness

[J65nko]

The program:

#!/bin/sh
    
THIS='   aa
bb
    cc
dd
ee
ff'
    
THAT="   zz
yy
    xx
ww
"

echo \"THIS: [\${THIS}]\"    
echo -------------------
echo "THIS: [${THIS}]"

echo

echo THIS: [\${THIS}]
echo -------------------
echo THIS: [${THIS}]

echo

echo \"THAT: [\${THAT}]\"
echo -------------------
echo "THAT: [${THAT}]"

echo

echo THAT: [\${THAT}]
echo -------------------
echo THAT: [${THAT}]

A run and the output

$ sh this-that
"THIS: [${THIS}]"
-------------------
THIS: [   aa
bb
    cc
dd
ee
ff]

THIS: [${THIS}]
-------------------
THIS: [ aa bb cc dd ee ff]

"THAT: [${THAT}]"
-------------------
THAT: [   zz
yy
    xx
ww
]

THAT: [${THAT}]
-------------------
THAT: [ zz yy xx ww ]

Who can explain?

[TerryP]

What were you expecting? Looks perfectly normal to me J65nko but I'm a bit drowsy....

Terry@vectra$ echo `cat this-that`
#!/bin/sh THIS=' aa bb cc dd ee ff' THAT=" zz yy xx ww " echo \"THIS: [\${THIS}]\" echo ------------------- echo "THIS: [${THIS}]" echo echo THIS: [\${THIS}] echo ------------------- echo THIS: [${THIS}] echo echo \"THAT: [\${THAT}]\" echo ------------------- echo "THAT: [${THAT}]" echo echo THAT: [\${THAT}] echo ------------------- echo THAT: [${THAT}]

Originally Posted by 2.6.3 Command Substitution

The shell shall expand the command substitution by executing command in a subshell environment (see Shell Execution Environment) and replacing the command substitution (the text of command plus the enclosing "$()" or backquotes) with the standard output of the command, removing sequences of one or more <newline>s at the end of the substitution. Embedded <newline>s before the end of the output shall not be removed; however, they may be treated as field delimiters and eliminated during field splitting, depending on the value of IFS and quoting that is in effect.

Originally Posted by 2.2.3 Double Quotes

Enclosing characters in double-quotes ( "" ) shall preserve the literal value of all characters within the double-quotes, with the exception of the characters dollar sign, backquote, and backslash, as follows:

There might be more HERE, but I'm to sleepy to parse it right now.



echo "$THIS" preserves things just as you would expect, that's the double quotes job.

echo $THIS substitutes $THIS with the contents of the THIS variable, which I assume is subject to field splitting.

Unless you screw with IFS, echo $THIS should be equivalent to this:

echo    aa \
bb \
    cc \
dd \
ee \
ff'

Which contains the `words` aa, bb, cc, dd, ee, and ff, plus a new line; because of how the shell does input field splitting!



Maybe I'm just to sleepy or perhaps I missed some trick about the question?

[ephemera]

Originally Posted by J65nko

...
THAT=" zz
yy
xx
ww
"

...

echo THAT: [${THAT}][/code]

...

THAT: [ zz yy xx ww ][/code]Who can explain?

[, ], zz, yy, xx, ww become individual arguments (default IFS is whitespace) to the echo command & echo prints its arguments separated by a space.
You have used single/double quotes to define $THIS & $THAT respectively but it makes no difference as the quotes are not preserved in the shell variable.
Was that the question?

[J65nko]

I found in this in a on old dump(8) I restored 2 days ago. What else has a man to do on the second day of Christmas?

I cannot recall why I wrote it, probably to show somebody on bsdforums.org who had a problem with this, at least for most beginning sh programmers, whitespace madness.

Indeed it has like both of you mentioned something to do with 'IFS' (inter field separator), a shell variable holding the characters, the shell uses to break up a string into words.

$ X='x      y    z'

$ echo "$X"
x      y    z

$ echo $X
x y z

$ IFS_ORIG=$IFS
$ IFS=''

$ echo $X       
x      y    z

$ IFS=$IFS_ORIG
$ echo $X
x y z

As shown here, after setting IFS to nothing, the "echo $X" shows the original whitespace.

[TerryP]

Originally Posted by J65nko

I found in this in a on old dump(8) I restored 2 days ago. What else has a man to do on the second day of Christmas?

On the second day of Christmas, my dump restored to me two geeks and a shell script in a pear tree.



Sorry, couldn't resist