lang/bash/ RandomScripts

I have a few trivial programs: exists, allexist and filterstat (the latter because it is equivalent to files = filter(stat,glob("*")) and similar – it does not pass through unmatched wildcard names, unlike normal glob wildcard expansion. See below.

Waiting for things

Downloads

Waiting for Chrome downloads to finish (though will stall if a download is interrupted and the .crdownload is not removed.

while exists *.crdownload; do echo -ne "Waiting: $(date)\r"; sleep 1; done; echo

the echo -ne and echo at the end are only so that the text in the console changes so you know something's happenning.

Processes and Jobs

These are two Python scripts, lwn (launch with name

exists, allexist and filterstat

Perl makes such programs very short to write due to things like the assumed $_ in things like for(@ARGV) which is equivalent to for $_(@ARGV) and basically is equivalent to e.g. for $_ in @ARGV in a language like Python.

exists

Returns true provided at least one of its arguments exists

#!/usr/bin/env perl
for(@ARGV) { exit(0) if -e; }
exit(1)

allexist

Returns true unless at least one of its arguments does not exist. (Note: it returns true if given no arguments, whereas exists returns false with no arguments.)

#!/usr/bin/env perl
for(@ARGV) { exit(1) unless -e ; }
exit(0);

filterstat

Returns arguments if and only if they exist (i.e. filters out non-existent files)

#!/usr/bin/env perl
for(@ARGV) { print "$_\n" if -e; }