From: Derek Peschel <dpeschel@eskimo.com>
To: zsh-workers@sunsite.dk
Subject: BUG? - 4.0.2 - parameter substitution won't double backslashes in values
Date: Wed, 6 Feb 2002 20:39:26 -0800 [thread overview]
Message-ID: <20020206203926.A10484@eskimo.eskimo.com> (raw)
I want to write the elements of $dirstack out to a file, separated by
newlines. If an element in $dirstack contains a newline, I want to write
a backslash before the newline in the file. Parameter substitution
managed that:
print ${dirstack[0]/
/\\\\
}
But I also want to double any backslashes in $dirstack, and I haven't
managed to do that yet with parameter substitution. The backslash
sequences in the parameter seem to be interpreted before substitution
happens.
Suppose I have a subdirectory "a\bc" under my home directory.
print $dirstack[0]
/usr/home/dpeschel/ac
["\b" is a backspace]
print ${dirstack[0]/\\/\\\\}
/usr/home/dpeschel/ac
[no change]
print ${dirstack[0]/\\\\/\\\\\\\\}
/usr/home/dpeschel/ac
[no change]
print ${dirstack[0]/b/t}
/usr/home/dpeschel/a c
[the "\b" gets changed to "\t" which is a tab]
Then I thought of using a single backslash -- given that escape sequences
happen "at a lower level" than parameter substitution, and parameter-
substitution backslashes must be quoted, it makes a kind of sense that
an unquoted backslash would affect the version of the value with un-
processed escape sequences.
The result was really weird:
print ${dirstack[0]/\/t}
t/usr/home/dpeschel/ac
If there's another way to do this, aside from parameter substitution,
that would be OK.
I haven't yet tackled reading the items back from the file, but obviously
writing has to work first.
-- Derek
next reply other threads:[~2002-02-07 4:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-02-07 4:39 Derek Peschel [this message]
2002-02-07 10:33 ` Peter Stephenson
2002-02-07 13:19 ` Derek Peschel
2002-02-07 19:20 ` Bart Schaefer
2002-02-07 20:22 ` Derek Peschel
2002-02-07 21:00 ` Bart Schaefer
2002-02-08 9:29 ` Derek Peschel
2002-02-08 21:35 ` Bart Schaefer
2002-02-07 10:44 ` BUG? - 4.0.2 - " Sven Wischnowsky
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