Without the aid of the escape mechanism, how to put a raw string into a variable?
Hi guys and gals...
I have been racking my brains with this one and I can't find anything about it...
Consider the code and the results below:
Code:
#!/usr/local/bin/dash
# #!/bin/sh
# #!/bin/bash
# rawstring.sh
: > /tmp/rawstring
# ############# THIS WORKS ADMIRABLY! ##############
NUM=32
STRING=""
while [ ${NUM} -le 126 ]
do
printf \\$( printf "%03o" "${NUM}" ) >> /tmp/rawstring
NUM=$(( NUM + 1 ))
done
STRING=$( cat /tmp/rawstring )
echo ""
/bin/echo "${STRING}"
echo ""
echo "${STRING}"
# ########## END OF THIS WORKS ADMIRABLY! ##########
# ##################################################
# THIS HOWEVER FAILS CATASTROPHICALLY!
echo ""
echo "This is where the error is with or without leading and trailing"
echo "single or double quotes:-"
echo ""
STRING=' !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~'
# The line below does not even get executed!
echo "${STRING}"
# ##################################################
Results on OSX 10.14.x:
Code:
Last login: Sun Apr 12 09:52:48 on ttys000
AMIGA:amiga~> cd Desktop/Code/Shell
AMIGA:amiga~/Desktop/Code/Shell> ./rawstring.sh
!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
This is where the error is with or without leading and trailing
single or double quotes:-
./rawstring.sh: 33: ./rawstring.sh: Syntax error: "(" unexpected
AMIGA:amiga~/Desktop/Code/Shell> _
As you can see saving a rawstring to disk and retrieving it again works but trying to force a rawstring without the escape mechanism fails catastrophically.
This is one of the USEFUL uses of 'cat' as it works admirably in this case but it requires I/O to do so...
I need to avoid the use of the escape mechanism inside the failing condition in case I want to __edit__ said rawstring inside any code.
I would like to know what is different about putting a rawstring into a variable using 'cat' and attempting to do so using hard coding.
# The line below does not even get executed!
echo "${STRING}"
.
.
.
Of course not - it is part of the single quoted literal string started with the very last character two lines above.
I'm afraid you won't escape escaping in some way. Try e.g. using this mechanism man bash:
Quote:
Quoting:
Words of the form $'string' are treated specially. The word expands to string, with backslash-escaped characters replaced as specified by the ANSI C standard. Backslash escape sequences, if present, are decoded as follows: ...
Now the fence is a custom word.
You must quote it to prevent variable substitutions.
BTW if a file or a here doc has got one line then read is smarter than cat.
Now the fence is a custom word.
You must quote it to prevent variable substitutions.
BTW if a file or a here doc has got one line then read is smarter than cat.
Code:
Last login: Sun Apr 12 14:58:50 on ttys000
AMIGA:amiga~> read STRING <<"EOT"
> !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
> EOT
AMIGA:amiga~>
AMIGA:amiga~> echo "${STRING}"
!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_`abcdefghijklmnopqrstuvwxyz{|}~
AMIGA:amiga~>
AMIGA:amiga~> # The space is missing!
AMIGA:amiga~>
AMIGA:amiga~> # Also the '\' too.
AMIGA:amiga~>
AMIGA:amiga~> echo "${#STRING}"
93
AMIGA:amiga~> # Should be 95.
AMIGA:amiga~>
AMIGA:amiga~> read -r STRING <<"EOT"
> !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
> EOT
AMIGA:amiga~> echo "${STRING}"
!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
AMIGA:amiga~>
AMIGA:amiga~> # The space is still missing.
AMIGA:amiga~>
AMIGA:amiga~> echo "${#STRING}"
94
AMIGA:amiga~> _
cat does not omit the space, (decimal character 32).
--- Post updated at 05:11 PM ---
Hi Rudic...
(HOPEFULLY THIS DOES NOT ATTACH TO THE PREVIOUS, if it does apologies...)
Code:
Last login: Sun Apr 12 15:58:43 on ttys000
AMIGA:amiga~> cd Desktop/Code/Shell
AMIGA:amiga~/Desktop/Code/Shell> ./rawstr.sh
Raw string:-
!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
Number of characters:-
98
Raw string:-
!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
Number of characters:-
95
Look at the real string inside the environment:-
Apple_PubSub_Socket_Render='/private/tmp/com.apple.launchd.glJfvo3uxT/Render'
HOME='/Users/amiga'
IFS='
'
LANG='en_GB.UTF-8'
LINENO=''
LOGNAME='amiga'
OLDPWD='/Users/amiga'
OPTIND='1'
PATH='/Library/Frameworks/Python.framework/Versions/3.8/bin:/Library/Frameworks/Python.framework/Versions/3.5/bin:/Users/amiga/Programs:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin'
PPID='4629'
PS1='AMIGA:\u\w> '
PS2='> '
PS4='+ '
PWD='/Users/amiga/Desktop/Code/Shell'
SHELL='/bin/bash'
SHLVL='1'
SSH_AUTH_SOCK='/private/tmp/com.apple.launchd.gtetHEIugk/Listeners'
STRING=' !"#$%&'"'"'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~'
TERM='xterm-256color'
TERM_PROGRAM='Apple_Terminal'
TERM_PROGRAM_VERSION='421.2'
TERM_SESSION_ID='8D9826C6-8625-4C9F-A6C9-E7CBDDEAC0CE'
TMPDIR='/var/folders/9c/bb_c667j5nj5cbbkw__1l8n40000gp/T/'
USER='amiga'
XPC_FLAGS='0x0'
XPC_SERVICE_NAME='0'
_='./rawstr.sh'
AMIGA:amiga~/Desktop/Code/Shell> _
Thanked your previous post...
Code:
#!/usr/local/bin/dash
# rawstr.sh
STRING=' !"#$%&\047()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~'
# Assumption that this is using dash's builtin 'echo'...
echo ""
echo "Raw string:-"
echo "${STRING}"
echo "Number of characters:-"
echo "${#STRING}"
STRING=$( echo "${STRING}" )
echo ""
echo "Raw string:-"
echo "${STRING}"
echo "Number of characters:-"
echo "${#STRING}"
echo ""
echo "Look at the real string inside the environment:-"
echo ""
set
# YES! (Fist in the air!)
# Nice one RudiC, I now have an idea for a convoluted means
# editing a raw ASCII string variable in POSIX mode and will
# upload IF it works at a later date...
OSX 10.14.x, default bash terminal, calling dash inside the code...
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