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Bash - Inserting non printable character(s) in string variable

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# 1  
Old 12-18-2015
Bash - Inserting non printable character(s) in string variable
Hello.
I have a string variable named L_TEMP to test a very simple filter.
L_TEMP="50AwL.|KWp9jk"
I want to insert a non printable character [ 0x00 - 0x1F ] between K and W.
I have try this :
Code:
linux-g65k:~ # a='50AwL.|K'
linux-g65k:~ # b='Wp9jk'
linux-g65k:~ # L_TEMP="$a$'\x07'$b"
linux-g65k:~ # echo "PATTERN : $L_TEMP"
PATTERN : 50AwL.|K$'\x07'Wp9jk
linux-g65k:~ # L_TEMP_TEST=$(echo "$L_TEMP"  | grep -E "[[:print:]]")
linux-g65k:~ # echo $L_TEMP_TEST
50AwL.|K$'\x07'Wp9jk
linux-g65k:~ # 
linux-g65k:~ #

The result should be :
Code:
linux-g65k:~ # a='50AwL.|K'
linux-g65k:~ # b='Wp9jk'
linux-g65k:~ # L_TEMP="$a$'\x07'$b"
linux-g65k:~ # echo "PATTERN : $L_TEMP"
PATTERN : 50AwL.|KWp9jk
linux-g65k:~ # L_TEMP_TEST=$(echo "$L_TEMP"  | grep -E "[[:print:]]")
linux-g65k:~ # echo $L_TEMP_TEST

linux-g65k:~ # 
linux-g65k:~ #

Any help is welcome
# 2  
Old 12-18-2015
Try
Code:
L_TEMP=$a$'\x07'$b

or
Code:
L_TEMP=$a$'\a'$b

This User Gave Thanks to RudiC For This Post:
jcdole
# 3  
Old 12-18-2015
My filter is :
Code:
L_TEMP_TEST=$(echo "$L_TEMP"  | grep -E "[[:print:]]")

My filter is malformed.
I want to exclude any value which does not contains exclusively printable character.
Code:
L_TEMP=$a$'\x07'$b
L_TEMP_TEST=$(echo "$L_TEMP"  | grep -E "[[:print:]]")

L_TEMP_TEST should be null
What is the good filter ?
Any help is welcome
# 4  
Old 12-18-2015
Not sure I understand. You want to eliminate non-printable chars from a string?
# 5  
Old 12-18-2015
Quote:
Originally Posted by RudiC
Not sure I understand. You want to eliminate non-printable chars from a string?
in pseudo code :
Code:
 MY_VAR=$L_TEMP
while read -N 1 ; do
   A_CHAR="$REPLY"
   if [[ $A_CHAR is not A_PRINTABLE_CHARACTER ]] ; then
    MY_VAR=""
    break
   fi
done <<<"$L_TEMP"

if [[ ! z $MY_VAR ]] ; then
    OK KEEP MY_VAR
else
    CALCULATE ANOTHER MY_VAR
fi

MY_VAR should set to null if it contains one or more not printable character
Somethings like
Code:
grep -E "[all characters are printable]"

my current filter is
Code:
grep -E "[one or more characters are printable]"

---------- Post updated at 13:09 ---------- Previous update was at 12:54 ----------

I have try
Code:
grep -e '[^[:print:]]'

Which seems not working
# 6  
Old 12-18-2015
You could use
Code:
echo $L_TEMP | grep -v "[^[:print:]]"

or, with a recent shell,
Code:
L_TEMP_TEST=${L_TEMP//[[:print:]]}

The second would leave L_TEMP_TEST empty if no non-printable chars are in the variable, or the non-printable chars only if there were.
This User Gave Thanks to RudiC For This Post:
jcdole
# 7  
Old 12-18-2015
That works
Great
Thank you very much
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