Commands by totoro (6)

  • If you enable multiuser, then you can permit others to share your screen session. The following conditions apply: 1. screen must be suid root; 2. "multiuser on" must be configured in ~/.screenrc; 3. control the others user(s) access with "aclchg": # ----- from ~/.screenrc-users ----- aclchg someuser +rx "#?" #enable r/o access to "someuser" aclchg someuser -x "#,at,aclchg,acladd,acldel,quit" # don't allow these aclchg otheruser +rwx "#?" # enable r/w access to "otheruser" aclchg otheruser -x "#,at,aclchg,acladd,acldel,quit" # don't allow them to use these commands # ----- After doing this (once), you start your session with: $ screen Then, the other user can join your terminal session(s) with youruserid: $ screen -r youruserid/ Note: the trailing "/" is required. Multiple users can share the same screen simultaneously, each with independent access controlled precisely with "aclchg" in the ~/.screenrc file. I use the following setup: # ~/.screenrc-base # default screenrc on any host source $HOME/.screenrc-base source $HOME/.screenrc-$HOST source $HOME/.screenrc-users # ----- Then, the base configurations are in ~/.screenrc-base; the host-specific configurations are in ~/.screenrc-$HOST, and the user configurations are in ~/.screenrc-users. The host-specific .screenrc file might contain some host-specific screen commands; e.g.: # ~/.screen-myhost # ----- screen -t 'anywhere' /bin/tcsh screen -t 'anywhere1' /bin/tcsh # ---- The .screenrc-base contains: # ~/.screenrc-base ## I find typing ^a (Control-a) awkward. So I set the escape key to CTRL-j instead of a. escape ^Jj termcapinfo xterm* [email protected]:[email protected]: autodetach on zombie kr verbose on multiuser on

    % screen -r someuser/
    totoro · 2009-03-25 23:59:38 1
  • If you have lots of remote hosts sitting "behind" an ssh proxy host, then there is a special-case use of "rsynch" that allows one to easily copy directories and files across the ssh proxy host, without having to do two explicit copies: the '-e' option allows for a replacement "rsh" command. We use this option to specify an "ssh" tunnel command, with the '-A' option that causes authentication agent requests to be forwarded back to the local host. If you have ssh set up correctly, the above command can be done without any passwords being entered.

    rsync -avz -e 'ssh -A sshproxy ssh' srcdir remhost:dest/path/
    totoro · 2009-03-25 21:29:07 5
  • Many Mac OS X programs, especially those in Microsoft:Office, create ASCII files with lines terminated by CRs (carriage returns). Most Unix programs expect lines separated by NLs (newlines). This little command makes it trivial to convert them. Show Sample Output

    function crtonl { perl -i -ape 's/\r\n?/\n/g;' $* ; }
    totoro · 2009-03-25 20:28:32 6
  • This little command (function) shows the CSV header fields (which are field names separated by commas) as an ordered list, clearly showing the fields and their order. Show Sample Output

    function headers { head -1 $* | tr ',' '\12' | pr -t -n ; }
    totoro · 2009-03-25 20:07:47 0
  • Coming back to a project directory after sometime elsewhere? Need to know what the most recently modified files are? This little function "t" is one of my most frequent commands. I have a tcsh alias for it also: alias t 'ls -ltch \!* | head -20' Show Sample Output

    function t { ls -ltch $* | head -20 ; }
    totoro · 2009-03-25 20:05:52 1
  • Ever wanted to find the most recently modified files, but couldn't remember exactly where they were in a project directory with many subdirectories? The "find" command, using a combination of "-mtime -N" and "-depth -D" can be used to find those files. If your directory structure isn't very deep, just omit the "-depth -D", but if your directory structure is very deep, then you can limit the depth of the traversal using "-depth -D", where "D" is the maximum number of directory levels to descend. Show Sample Output

    find . -type f -depth -3 -mtime -5
    totoro · 2009-03-25 19:54:06 0

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back ssh from firewalled hosts
host B (you) redirects a modem port (62220) to his local ssh. host A is a remote machine (the ones that issues the ssh cmd). once connected port 5497 is in listening mode on host B. host B just do a ssh -p 5497 -l user and reaches the remote host'ssh. This can be used also for vnc and so on.

Print all git repos from a user
in case you could afford installing jq

Huh? Where did all my precious space go ?
Sort ls output of all files in current directory in ascending order Just the 20 biggest ones: $ ls -la | sort -k 5bn | tail -n 20 A variant for the current directory tree with subdirectories and pretty columns is: $ find . -type f -print0 | xargs -0 ls -la | sort -k 5bn | column -t And finding the subdirectories consuming the most space with displayed block size 1k: $ du -sk ./* | sort -k 1bn | column -t

Sort all running processes by their memory & CPU usage
you can also pipe it to "tail" command to show 10 most memory using processes.

Convert .flv to .3gp
Download YouTube videos as .flv and convert them to .3gp for your mobile phone.

Empty the linux buffer cache

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Validate openssh key & print checksum

Generate RSA private key and self-signed certificate
This will create, in the current directory, a file called 'pk.pem' containing an unencrypted 2048-bit RSA private key and a file called 'cert.pem' containing a certificate signed by 'pk.pem'. The private key file will have mode 600. !!ATTENTION!! ==> this command will overwrite both files if present.

Find out if a module is installed in perl
Shows the path if the module is installed or exit quietly (to simply avoid the 'No documentation found' msg).

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