I want to write a script that renames the pages of a DJVU file recursively. From http://djvu.sourceforge.net/doc/man/djvused.html I know that the command to do that on a single page (say call page 5 of the bundle with name 6) is
djvused file.djvu -e 'select 5; set-page-title 6; save'
But then I have troubles when trying to do it recursively, namely running the script
./for.sh
which is given by
for (( i=12; i<=823; i++ ))
do
djvused file.djvu -e 'select $i; set-page-title $((i-10)); save'
done
The error I get is due to the program being unable to understand $i as a number, instead of an expression. I think this is related to my small knowledge of shell scripts and djvused.
Could anyone tell me how to modify it so that it works?
You should quote it properly with double-quotes. Using single quotes would not allow variables to be expanded and remain as literal form.
for (( i=12; i<=823; i++ ))
do
djvused file.djvu -e "select $i; set-page-title $((i-10)); save"
done
As noted about single quotes:
Enclosing characters in single quotes (‘'’) preserves the literal value of each character within the quotes. A single quote may not occur between single quotes, even when preceded by a backslash.
Whereas on double quotes:
Enclosing characters in double quotes (‘"’) preserves the literal value of all characters within the quotes, with the exception of ‘$’, ‘
’, ‘\’, and, when history expansion is enabled, ‘!’. The characters ‘$’ and ‘’ retain their special meaning within double quotes