Commands by postrational (5)

  • Pass TAB as field separator to sort, join, cut, etc.

    Use this BASH trick to create a variable containing the TAB character and pass it as the argument to sort, join, cut and other commands which don't understand the \t notation. sort -t $'\t' ... join -t $'\t' ... cut -d $'\t' ... Show Sample Output


    5
    sort -t $'\t' -k 2 input.txt
    postrational · 2010-07-11 12:58:51 5
  • Short one line while loop that outputs parameterized content from one file to another

    There is a common command for outputting a field or list of fields from each line in a file. Why wouldn't you just use cut?


    4
    cut -f 1 three-column.txt > first-column.txt
    postrational · 2010-07-11 10:13:45 7
  • Perform a reverse DNS lookup

    Performs a reverse DNS lookup, variants include: nslookup 74.125.45.100 or: host 74.125.45.100 Show Sample Output


    4
    dig -x 74.125.45.100
    postrational · 2009-09-28 15:13:34 3
  • save date and time for each command in history

    Date-time format: YYYY-MM-DD HH:MM:SS Show Sample Output


    7
    export HISTTIMEFORMAT='%F %T '
    postrational · 2009-09-26 17:13:23 7
  • Check your unread Gmail from the command line

    Checks the Gmail ATOM feed for your account, parses it and outputs a list of unread messages. For some reason sed gets stuck on OS X, so here's a Perl version for the Mac: curl -u username:password --silent "https://mail.google.com/mail/feed/atom" | tr -d '\n' | awk -F '<entry>' '{for (i=2; i<=NF; i++) {print $i}}' | perl -pe 's/^<title>(.*)<\/title>.*<name>(.*)<\/name>.*$/$2 - $1/' If you want to see the name of the last person, who added a message to the conversation, change the greediness of the operators like this: curl -u username:password --silent "https://mail.google.com/mail/feed/atom" | tr -d '\n' | awk -F '<entry>' '{for (i=2; i<=NF; i++) {print $i}}' | perl -pe 's/^<title>(.*)<\/title>.*?<name>(.*?)<\/name>.*$/$2 - $1/' Show Sample Output


    47
    curl -u username:password --silent "https://mail.google.com/mail/feed/atom" | tr -d '\n' | awk -F '<entry>' '{for (i=2; i<=NF; i++) {print $i}}' | sed -n "s/<title>\(.*\)<\/title.*name>\(.*\)<\/name>.*/\2 - \1/p"
    postrational · 2009-09-07 21:56:40 54

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

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)

fetch all revisions of a specific file in an SVN repository
Manages everything through one sed script instead of pipes of greps and awks. Quoting of shell variables is generally easier within a sed script.

Url Encode
Converts reserved characters in a URI to their percent encoded counterparts. Alternate python version: $ echo "$url" | python -c 'import sys,urllib;print urllib.quote(sys.stdin.read().strip())'

external projector for presentations
i spent way too many hours trying to fiddle with /etc/X11/xorg.conf trying to hook up various external projectors. too bad i didn't know this would solve all my problems.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

set a reminder for 5 days in the future
setup for reminder in 5 days, added the date in the future. To run a job at 4pm three days from now, you would do at 4pm + 3 days, to run a job at 10:00am on July 31, you would do at 10am Jul 31 and to run a job at 1am tomorrow, you would do at 1am tomorrow.

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

Rename files in batch

Edit a file inside a compressed archive without extracting it
If you vim a compressed file it will list all archive content, then you can pickup any of them for editing and saving. There you have the modified archive without any extra step. It supports many file types such as tar.gz, tgz, zip, etc.

cpu info

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: