Commands by kFiddle (10)

  • The symlinks command can show status of all symbolic links, including which links are dangling, which symlinks point to files on other file systems, which symlinks use ../ more than necessary, which symlinks are messy (e.g. having too many slashes or dots), etc. Other useful things it can do include removing all dangling links (-d) and converting absolute links to relative links (-c). The path given must be an absolute path (which is why I used $(pwd) in the example command).


    6
    symlinks -r $(pwd)
    kFiddle · 2009-05-01 23:33:10 1
  • Most of you are probably familiar with the "apropos" command for searching man pages. However, did you know there's a similar command inside of gdb? If, for example, you wanted to know all gdb commands that related to threads, you could type "apropos thread". Type "help some_command" to receive more information about a command. Type "help" by itself to see a list of help topics.


    0
    gdb command: apropos <keyword>
    kFiddle · 2009-05-01 23:19:35 0
  • Sometimes "ls" is just too slow, especially if you're having problems with terminal scroll speed, or if you're a speed freak. In these situations, do an echo * in the current directory to immediately see the directory listing. Do an echo * | tr ' ' '\n' if you want a column. Do an alias ls='echo *' if you want to achieve higher echelons of speed and wonder. Note that echo * is also useful on systems that are so low in memory that "ls" itself is failing - perhaps due to a memory leak that you're trying to debug.


    -5
    echo *
    kFiddle · 2009-04-17 21:40:58 5
  • I've seen some versions of hostname that don't have the -i option, so this may not work everywhere. When available, it's a better alternative than using ifconfig and wasting eyeball muscle to search for the address, and it's definitely simpler than using awk/sed.


    -2
    hostname -i
    kFiddle · 2009-04-17 21:26:56 3
  • This is a simple command, but extremely useful. It's a quick way to search the file names in the current directory for a substring. Normally people use "ls *term*" but that requires the stars and is not case insensitive. Color (for both ls and grep) is an added bonus.


    6
    alias lg='ls --color=always | grep --color=always -i'
    kFiddle · 2009-04-11 23:15:12 3
  • Reduce the number of keystrokes it takes to open a file in vim. First of all, you just need to type "v", which is less than half the number of characters (!), and second-of-all, you only need to enter a substring of the file you want to open. For example, if you want to open the file, homework.txt, then type "v hom" to open it. Good tip is to use the lowest unique substring, otherwise you'll open multiple files in different buffers (which is sometimes desirable). Use Ctrl-^ to switch between buffers.


    0
    function v { if [ -z $1 ]; then vim; else vim *$1*; fi }
    kFiddle · 2009-04-11 23:06:43 2
  • This example, for example, produces the output, "Fri Feb 13 15:26:30 EST 2009"


    48
    kFiddle · 2009-04-11 22:26:41 7
  • Have a grudge against someone on your network? Do a "find -writable" in their directory and see what you can vandalize! But seriously, this is really useful to check the files in your own home directory to make sure they can't inadvertently be changed by someone else's wayward script.


    4
    find -writable
    kFiddle · 2009-04-11 22:16:35 0
  • Info has some of the worst keybindings I've ever seen. Being a vim user, I attribute that to emacs influence. Use the --vi-keys option to use some of the vi keybindings, although this won't change all the keybindings. Use the "infokey" program to have more control over info keybindings.


    8
    info --vi-keys
    kFiddle · 2009-04-11 22:10:08 4
  • Although less behaves more or less like vim in certain aspects, the vim regex for word boundaries (\< and \>) do not work in less. Instead, use \b to denote a word boundary. Therefore, if you want to search for, say, the word "exit", but do not want to search for exiting, exits, etc., then surround "exit" with \b. This is useful if you need to search for specific occurrences of a keyword or command. \b can also be used at just the beginning and end, if needed.


    5
    \bTERM\b
    kFiddle · 2009-04-11 22:05:12 1

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Check These Out

List all symbolic links in current directory
Many competing commands to do this, but since most people want a Long list with Human readable files sizes and want to see All files (including hidden (.*) files) this one wins on simplicity and usefulness. Plus grep is just as, if not more portable than sed or awk, and is more widely understood. :)

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

grep for minus (-) sign
Use flag "--" to stop switch parsing

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

Working random fact generator
Though without infinite time and knowledge of how the site will be designed in the future this may stop working, it still will serve as a simple straight forward starting point. This uses the observation that the only item marked as strong on the page is the single logical line that includes the italicized fact. If future revisions of the page show failure, or intermittent failure, one may simply alter the above to read. $ wget randomfunfacts.com -O - 2>/dev/null | tee lastfact | grep \ | sed "s;^.*\(.*\).*$;\1;" The file lastfact, can then be examined whenever the command fails.

Create a mirror of a local folder, on a remote server
Create a exact mirror of the local folder "/root/files", on remote server 'remote_server' using SSH command (listening on port 22) (all files & folders on destination server/folder will be deleted)

Extract IPv4 addressess from file

find process associated with a port
e.g. fuser 25/tcp (see which pid is listening on smtp)

Backup your OpenWRT config (only the config, not the whole system)
You only have to fill in your administrative account and password, and the router FQDN! I recommand to execute this command not over the internet, because there is no encryption (the username and password will be transmitted in plaintext!)

run a command from within vi without exiting
":! ls -l " results in listing the files in the current directory. pressing "enter" will get you back into vi.


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