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Old 03-31-2016, 11:55 AM   #1
Paul_N
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shell: how to escape (or not escape) $ within an echo statement?


I'm new to shell programing, and what I'm trying to do may be a little silly, but I'd like to use ECHO within the shell to build a Perl script that will be later executed by that same shell program. the problem i'm having is how to escape the $ character within the echo line to get what i want, as well as issues of quotes within quotes.

so here's a piece of my shell script

Quote:
# make the date string for yesterday
NOW=$(date -d "1 day ago" '+%y%m%d')
# make a line to put in perl file
echo "$ftp->put("/home/pi/bin/log$NOW.txt") || die $ftp->message;" >> ftplogs.pl

if today is Mar 30, then the value of $NOW is 160329 (the day before)

and what I want to go into the file "ftplogs.pl" from line 4 in my script is:

$ftp->put("/home/pi/bin/log160329.txt") || die $ftp->message;

so I need to somehow get "$ftp-put" and "$ftp->message" to be output just as the are, and yet I also want $NOW to be converted to 160329.

so how to I escape $ftp-put and ftp->message so that that's what is produced, and how to I quote this line? single quotes, double quotes? and how to I escape the quotes so that I get quotes in the output file when I want them?

thanks for any advice offered.

Last edited by Paul_N; 03-31-2016 at 12:03 PM.
 
Old 03-31-2016, 12:13 PM   #2
grail
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Backslash (\) is the escape character for many languages, including bash
 
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Old 04-05-2016, 02:59 AM   #3
ondoho
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Code:
echo "\$ftp->put("/home/pi/bin/log$NOW.txt") || die \$ftp->message;" >> ftplogs.pl
you might need to escape more characters, i don't know.
the way you are going about this seems overly complex, but if it's just a brain teaser, why not...

otoh, i once made a shell script that produces conky syntax, and to me it's very useful. lots of escaped $ in there.
 
  


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