SUBST (1)
substitute definitions into file(s)
SYNOPSIS
subst
[
-e
editor
]
-f
substitutions
victim ...
DESCRIPTION
Subst
makes substitutions into files, in a way that is suitable for customizing
software to local conditions.
Each
victim
file
is altered according to the contents of
the
substitutions
file.
The
substitutions
file contains one line per substitution.
A line consists of two fields separated by one or more tabs.
The first field is the name of the substitution, the second
is the value.
Neither should contain the character ``#'', and use of text-editor
metacharacters like ``&'' and ``\e'' is also unwise;
the name in particular is best restricted to be alphanumeric.
A line starting with ``#'' is a comment and is ignored.
In the victims,
each line on which a substitution is to be made
(a target line)
must be preceded by a
prototype line.
The prototype line should be delimited in such a way that it will be
taken as a comment by whatever program processes the file later.
The prototype line must contain a ``prototype'' of the target line bracketed
by ``=()<'' and ``>()='';
everything else on the prototype line is ignored.
Subst
extracts the prototype, changes all instances of substitution names
bracketed by ``@<'' and ``>@'' to their values,
and then replaces the target line with the result.
OPTIONS
-e
Substitutions are done using the
sed (1)
editor, which must be found in either the
/bin
or
/usr/bin
directories.
To specify a different executable, use the ``-e'' flag.
EXAMPLE
\w'SECOND'u+4n
FIRST 111
SECOND 222
and the victim file is
x = 2;
/* =()<y = @<FIRST>@ + @<SECOND>@;>()= */
y = 88 + 99;
z = 5;
then ``subst -f substitutions victim'' changes victim to:
x = 2;
/* =()<y = @<FIRST>@ + @<SECOND>@;>()= */
y = 111 + 222;
z = 5;
FILES
\w'\fIvictimdir\fP/substtmp.old'u+4n
victimdir/substtmp.new new version being built
victimdir/substtmp.old old version during renaming
SEE ALSO
DIAGNOSTICS
Complains and halts if it is unable to create its temporary files
or if they already exist.
HISTORY
Written at U of Toronto by Henry Spencer.
Rich $alz added the ``-e'' flag July, 1991.
BUGS
When creating a file to be substed, it's easy to forget to insert
a dummy target line after a prototype line;
if you forget, subst ends up deleting whichever line did in fact
follow the prototype line.
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