Re^2: disk space utilization

Perl's "-a" command-line option allows you to pretend that you're using something that resembles "awk" (that's why it's "-a") -- differences between "perl -a" and "awk" are that perl uses @F where awk uses $1,$2,..., and the first token on the line is $F[0] instead of $1:

 df -k | perl -lane 'print $F[3]'
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(the "-l" option helps make line-feed handling more like awk as well). I presume this still doesn't do exactly what the OP intended, since it prints a line of output for every line of input from "df -k"; but the OP's use of "grep '/^' " seems odd -- not sure what's intended by that.

To limit the output to a particular line, one can cite the target path as an arg to "df", and/or use a condition in the perl script:

 df -k / | perl -lane 'print $F[3] if /\d/' # skips column headings

# or just:

 df -k | perl -lane 'print $F[3] if m{/$}'  # only prints value for "/
+"
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Re^3: disk space utilization by ministry (Scribe) on Apr 12, 2005 at 15:49 UTC
Thanks for the info graff, the use of an expression grep "/^" in the middle of my arguement will only report back the line of output in the `df -k` that has a slash that is immediately followed by an end of line tag (anchor)- thereby only returning the root partition, as opposed to only doing a basic grep for a slash, which will return every slice starting with a slash (working in ksh). Is there any way I can incorporate your 'one-liner' into my script? As this is only one function out of several that needs to be performed. Good judgement comes with experience. Unfortunately, the experience usually comes from bad judgement.	[reply] [d/l]
Re^4: disk space utilization by graff (Chancellor) on Apr 14, 2005 at 03:34 UTC
If what you want is to get the available space on a specific disk volume from within a perl script, I'd do something like this: my $targ_vol = "/"; my @df_output = `df -k $targ_vol`; # output should be two lines: # first line is column headings, second line is data my %df_data; if ( @df_output ) { my @headings = split( /\s+/, $df_output[0] ); my @data = split( /\s+/, $df_output[1] ); @df_data{@headings} = @data; } print "available on $targ_vol: $df_data{Avail}\n"; # (your version of df might use some string similar to but different f +rom "Avail") [download] You shouldn't have a problem if you're just looking at "/". (update: if you're looking at some path other than "/", you need to be careful about knowing whether it's on some different file system, and figuring out whether that file system is currently mounted -- if it isn't, df will give you info about "/" instead. And God help you if it's mounted as NFS, and the NFS server has gone down...) (update: BTW, when I try "df \| egrep '/^'", nothing comes out, which is what I would expect; but if I do "df \| egrep '/$'", I get the line that ends with a slash. That's what I don't understand about your usage in the OP -- I think it can't work as posted, unless your "egrep" is way different from mine...)	[reply] [d/l]