[FFmpeg-devel] [PATCH V4 2/2] configure: replace 'pr' with printf since busybox does not support pr

[avih]

>  log_file(){
>     log BEGIN $1
> -    pr -n -t $1 >> $logfile
> +    i=1

Shell variables are global. This means that any part of the code which ends
up calling `log_file` directly or through some other function (and not isolated
in a subshell) will get its `i` variable clobbered by `log_file`. This can be
very tricky to debug and identify.

Please use a variable name which is unlikely to be used by other functions,
like `log_file_i`. Same goes for `line` below. This is critical especially in
functions which end up get called by a lot of other function - like `log_file`.

> +    while read line;do

This needs to be `while IFS= read -r line; do`.

Without the IFS= part trailing white spaces will be trimmed, and without
the -r part backslash ('\') will be interpreted an an escape char.

> +        printf '%5s  %s\n' "${i}" "${line}"
> +        i=$(($i+1))
> +    done < $1 >> $logfile

While the previous version of the function used `$1` unquoted, it's generally
a very bad practice, as it cannot handle white spaces in file names and is
subjected to globbing and open for attacks. In general always quote _all_
strings unless you know for a fact that it's not required. In this case it _is_
required.

>     log END $1
> }