Commands by johnraff

Commands by johnraff (5)

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Selecting a random file/folder of a folder

Choose random file from current folder. Avoids using ls.
This is sample output - yours may be different.
-2

for i in *; do echo "$i"; done | shuf -n1

johnraff · 2011-03-17 17:48:42 5
recursive search and replace old with new string, inside files

If you can install rpl it's simpler to use and faster than combinations of find, grep and sed. See man rpl for various options. time on above operation: real 0m0.862s, user 0m0.548s, sys 0m0.180s using find + sed: real 0m3.546s, user 0m1.752s, sys 0m1.580s Show Sample Output
This is sample output - yours may be different.
```
john@raffles2:~/Desktop$rpl -R LOCALE LOC**E copy\ of\ ies4linux-2.99.0.1/ 
Replacing "LOCALE" with "LOC**E" (case sensitive) (partial words matched)
..............................................................
A Total of 189 matches replaced in 62 files searched.
```
3

$rpl -R oldstring newstring folder

johnraff · 2009-12-09 03:15:31 7
Make sure a script is run in a terminal.

If your script needs to be run in a terminal, this line at the top will stop it running if you absent-mindedly double-click the icon, perhaps intending to edit it. (Of course this won't help with scripts that run in the background.)
This is sample output - yours may be different.
0

tty > /dev/null 2>&1 || { aplay error.wav ; exit 1 ;}

johnraff · 2009-11-04 16:18:00 5
A function to find the newest file of a set.

Usage example: newest Desktop/* Replace "-nt" with "-ot" for oldest. Run shopt -s dotglob first to include dotfiles.
This is sample output - yours may be different.
1

newest () { candidate=''; for i in "$@"; do [[ -f $i ]] || continue; [[ -z $candidate || $i -nt $candidate ]] && candidate="$i"; done; echo "$candidate"; }

johnraff · 2009-10-29 17:35:01 2
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
This is sample output - yours may be different.
38

sudo touch /forcefsck

johnraff · 2009-10-29 17:04:47 14

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history autocompletion with arrow keys

This will enable the possibility to navigate in the history of the command you type with the arrow keys, example "na" and the arrow will give all command starting by na in the history.You can add these lines to your .bashrc (without &&) to use that in your default terminal.

Deal with dot files safely

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)

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" }

Get AWS temporary credentials ready to export based on a MFA virtual appliance

You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

Highlight network TX, RX information change

Sort on multiple dis-contiguous keys/fields (can even specify key number/field from the end)

Notes: 1) -n-1 means sort key is the last field 2) -l is important if each separate record is on a new line (usually so for text files) 3) -j tells msort not to create log file (msort.log) in the working directory 4) may need to install msort package. 5) msort does lot more. Check man msort

Remove all unused kernels with apt-get

Note the double space: "...^ii␣␣linux-image-2..." Like 5813, but fixes two bugs: [1]This leaves the meta-packages 'linux-headers-generic' and 'linux-image-generic' alone so that automatic upgrades work correctly in the future. [2]Kernels newer than the currently running one are left alone (this can happen if you didn't reboot after installing a new kernel). I'm bummed that this took 228 characters. I'd like to see a simpler version.

Command to logout all the users in one command

Just run it ;)

;)

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