{"id":607,"date":"2016-02-05T11:19:39","date_gmt":"2016-02-05T16:19:39","guid":{"rendered":"http:\/\/fazigu.org\/blog\/?p=607"},"modified":"2017-02-24T06:13:09","modified_gmt":"2017-02-24T11:13:09","slug":"shell-nuggets-quickie-tabulizer","status":"publish","type":"post","link":"https:\/\/fazigu.org\/blog\/2016\/02\/05\/shell-nuggets-quickie-tabulizer\/","title":{"rendered":"Shell Nuggets: Quickie Tabulizer"},"content":{"rendered":"

I’m real bad about things lining up. \u00a0Used to go out of my way to ensure variable declarations were columnized by access mode, type, name, equals sign and initial value.<\/p>\n

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final BufferedImage mapImg = MapImageFactory.newInstance(width, height);\r\nfinal int           count  = ad.getPosition() * 2;\r\n\r\nmapImg.composite(adImg, 25               , (this.adHeight + 20) * count + 20, Over);\r\nmapImg.composite(adTxt, 25 + this.adWidth, (this.adHeight + 20) * count + 20, Over);\r\n<\/pre>\n<\/blockquote>\n
The Tabularizer plugin<\/a>\u00a0for vim was a boon for productivity. \u00a0Well, mine. \u00a0For everyone else, it meant either destroying the pre-formatted beauty or re-aligning all the columns.<\/p>\n
Anyway, it’s considered bad practice, so I’ve tried to get away from it– at least when writing shared code. \u00a0I still like perfect tabular output in my day-to-day. \u00a0Take the df<\/code> command, for example. \u00a0It’s default “human readable sizes” output:<\/p>\n
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2016-02-05 11:03:57 \u00ab\u00ab\u00ab\u00ab ~\r\n rons@rons-VM$ df -h\r\nFilesystem            Size  Used Avail Use% Mounted on\r\n\/dev\/mapper\/VolGroup00-LogVol00\r\n                       59G   29G   27G  52% \/\r\n\/dev\/sda1              99M   33M   61M  36% \/boot\r\ntmpfs                 1.5G     0  1.5G   0% \/dev\/shm\r\n<\/pre>\n<\/blockquote>\n
Bleah. A line break. Why you mess my rows, GNU? An easy fix jumped into my noggin the other day and crept down my arms and out my fingertips:<\/p>\n
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2016-02-05 11:03:58 \u00ab\u00ab\u00ab\u00ab ~\r\n rons@rons-VM$ df -h | sed 's\/Mounted on$\/Mount\/;' | xargs printf '%-40.40s %8s %8s %8s %5s  %s\\n'\r\nFilesystem                                   Size     Used    Avail  Use%  Mount\r\n\/dev\/mapper\/VolGroup00-LogVol00               59G      29G      27G   52%  \/\r\n\/dev\/sda1                                     99M      33M      61M   36%  \/boot\r\ntmpfs                                        1.5G        0     1.5G    0%  \/dev\/shm\r\n<\/pre>\n<\/blockquote>\n
The trick is that a\u00a0printf<\/code>\u00a0format with a trailing newline will repeat if it runs out of input tokens. \u00a0 That’s why I had to truncate the “Mounted on” to just “Mount” above– otherwise there would be an irregular number of columns (and thus printf<\/code> tokens) on each line\/row. \u00a0Spaces in filesystems and mounts will mess it up, too, but if you use spaces in the names of your mounts, you deserve the dissonance.<\/p>\n
Edit: Better shell function replacement below.<\/p>\n
unset -f df ; function df() {\r\n  command df -P $@ | perl -ane '\r\n    push(@rows, [@F]);\r\n    for (0..$#F) {\r\n      $ll = length($F[$_]); $cm[$_] = $ll if $ll > ($cm[$_] \/\/ 0);\r\n    }\r\n    END { printf(\"%-$cm[0]s %$cm[1]s %$cm[2]s %$cm[3]s %$cm[4]s %s\\n\", @{$_})\r\n      for @rows; }';\r\n} ;<\/pre>\n
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Uses the -P flag for POSIX one-line-per-mount format. \u00a0 Dynamically calculates column widths.<\/p>\n
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