On Sun, May 14, 2017 at 07:02:41PM +1000, Tony White wrote:
#!/bin/sh # run this is script in the image folder # change the value 320 to whatever width you want response = 320 for f in *; do # prefix the results with sm_ or change to what you want convert $f -resize $response +profile "*" sm_$f done
You really should quote your variables. If any of the filenames have spaces (or other problematic characters like *, ?, [, (, and other characters with special meaning to the shell) in them, this script will break. Those are all valid characters in a filename on all linux filesystems. There are only two characters which are not valid in a filename, a forward-slash and a NUL byte. Anything else is permitted. To avoid any problems cause by such annoying characters, you should surround variables names with double-quotes when you use them, for the same reason you quoted the "*". e.g. convert "$f" -resize "$response" +profile "*" "sm_$f" There are other reasons to quote variables, especially when you can not have complete knowledge or control over the value of a variable. As a general rule, **ALWAYS** double-quote variables when you use them. It can pretty nearly never hurt to double-quote a variable, but there are plenty of situations using an unquoted variable can cause severe damage. (NOTE: there are some very specific rare situations where you don't want to and shouldn't quote variables, but if you´re capable of writing the kind of shell code that requires that, you'll know when not to quote. Otherwise, just quote variables all the time: 999999 times out of 1000000 (or more) it is exactly the right, safe, and correct thing to do. Or, to put it another way, unless you know exactly WHY you don't want to quote a specific variable, then quote it) BTW, this script has clearly not been tested - typed in from memory? There should be no space between the variable name, the equals sign, or the value being assigned. ´response=320' would assign the value 320 to the variable $response. 'response = 320' does not, it is an attempt to run a command called 'response' with two command line arguments '=' and '320'. Also BTW, use double-quotes when you need to interpolate variables or sub-shell results etc into a string, and it's best to use single-quotes otherwise, like so: convert "$f" -resize "$response" +profile '*' "sm_$f" That's the key difference between double and single-quotes - single-quotes are for static, fixed, literal strings. Double-quotes are for for variables and other dynamically generated output. Finally, when passing filename arguments to programs that understand the GNU convention of '--' to indicate the end of program options, it's also always a good idea to use it to prevent filenames beginning with a '-' from being interpreted as options. e.g. if a directory contains a file called '-rf' in it, there is a huge difference between running 'rm *' and 'rm -- *' craig -- craig sanders <cas@taz.net.au>