Commands by cout (6)

  • I like the other three versions but one uses nested loops and another prints every color on a separate line. Both versions fail to reset colors before giving the prompt back. This version uses the column command to print a table so all the colors fit on one screen. It also resets colors back to normal before as a last step.


    9
    for i in {0..255}; do echo -e "\e[38;05;${i}m${i}"; done | column -c 80 -s ' '; echo -e "\e[m"
    cout · 2010-07-21 17:30:36 1

  • -2
    find . -name '*.txt' | grep -v '\.lzma$' | xargs -n 1 lzma -f -v -3
    cout · 2010-07-21 16:58:41 1
  • This will cause bash to fix a garbled terminal before the prompt is printed. For example, if you cat a file with nonprintable character sequences, the terminal sometimes ends up in a mode where it only prints line drawing characters. This sequence will return the terminal to the standard character set after every command.


    5
    export PS1="\[\017\033[m\033[?9l\033[?1000l\]$PS1"
    cout · 2010-07-15 19:18:05 3
  • I used to do a lot of path manipulation to set up my development environment (PATH, LD_LIBRARY_PATH, etc), and one part of my environment wasn't always aware of what the rest of the environment needed in the path. Thus resetting the entire PATH variable wasn't an option; modifying it made sense. The original version of the functions used sed, which turned out to be really slow when called many times from my bashrc, and it could take up to 10 seconds to login. Switching to parameter substitution sped things up significantly. The commands here don't clean up the path when they are done (so e.g. the path gets cluttered with colons). But the code is easy to read for a one-liner. The full function looks like this: remove_path() { eval PATHVAL=":\$$1:" PATHVAL=${PATHVAL//:$2:/:} # remove $2 from $PATHVAL PATHVAL=${PATHVAL//::/:} # remove any double colons left over PATHVAL=${PATHVAL#:} # remove colons from the beginning of $PATHVAL PATHVAL=${PATHVAL%:} # remove colons from the end of $PATHVAL export $1="$PATHVAL" } append_path() { remove_path "$1" "$2" eval PATHVAL="\$$1" export $1="${PATHVAL}:$2" } prepend_path() { remove_path "$1" "$2" eval PATHVAL="\$$1" export $1="$2:${PATHVAL}" } I tried using regexes to make this into a cleaner one-liner, but remove_path ended up being cryptic and not working as well: rp() { eval "[[ ::\$$1:: =~ ^:+($2:)?((.*):$2:)?(.*):+$ ]]"; export $1=${BASH_REMATCH[3]}:${BASH_REMATCH[4]}; }; Show Sample Output


    0
    rp() { local p; eval p=":\$$1:"; export $1=${p//:$2:/:}; }; ap() { rp "$1" "$2"; eval export $1=\$$1$2; }; pp() { rp "$1" "$2"; eval export $1=$2:\$$1; }
    cout · 2010-07-15 18:52:01 62
  • Ssh to host1, host2, and host3, executing on each host and saving the output in {host}.log. I don't have the 'parallel' command installed, otherwise it sounds interesting and less cryptic.


    1
    for host in host1 host2 host3; do ssh -n user@$host <command> > $host.log & done; wait
    cout · 2010-07-14 14:55:31 0
  • I like this better than some of the alternatives using -exec, because if I want to change the string, it's right there at the end of the command line. That means less editing effort and more time to drink coffee. Show Sample Output


    2
    find . -name '*.?pp' | xargs grep -H "string"
    cout · 2010-07-14 14:41:07 2

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

Share Your Commands


Check These Out

Simple way to envoke a secure vnc session through ssh enabled router.
The ip address is of the remote machine running the vncserver. Must log in first to the router then the VNC session. Very nice if you have open-wrt or dd-wrt on your router.

list block devices
Shows all block devices in a tree with descruptions of what they are.

Run a file system check on your next boot.
The empty file /forcefsck causes the file system check fsck to be run next time you boot up, after which it will be removed. This works too: $sudo >/forcefsck

Create higher quality gif from videos
I had to compress it a bit to meet the 255 limit. See sample for full command (274) usage: ffgif foo.ext Supports 3 arguments (optional) ffgif filename seek_time time_duration scale ffgif foo 10 5 320 will seek 10 seconds in, convert for 5 seconds at a 320 scale. Default will convert whole video to gif at 320 scale. Inspiration - http://superuser.com/questions/556029/how-do-i-convert-a-video-to-gif-using-ffmpeg-with-reasonable-quality/556031#556031

SHA256 signature sum check of file
get the SHA256 sum signatur for a file

monitor network traffic and throughput in real time
see http://iptraf.seul.org/ for all kinds of documentation and screenshots

Twitpic upload and Tweet

Fibonacci numbers with awk
recursive version, "pure" AWK

Optimal way of deleting huge numbers of files

Determine what version of bind is running on a dns server.
Due to the recent dynamic update vulnerability with bind, I was forced to dig a little deeper into dig...


Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for: