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 7
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 10
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 6
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 3
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 19

What's this?

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Jump to line X in file in Nano.

Starts the cursor on line X of file foo. Useful for longer files in which it takes a long time to scroll. If X is greater than the number of lines in file foo, it will go to the last existing line.

Create date based backups

This script creates date based backups of the files. It copies the files to the same place the original ones are but with an additional extension that is the timestamp of the copy on the following format: YearMonthDay-HourMinuteSecond

Recursively remove .svn directories

list with full path

Create a 100MB file for testing transfer speed

randomize hostname and mac address, force dhcp renew. (for anonymous networking)

this string of commands will release your dhcp address, change your mac address, generate a new random hostname and then get a new dhcp lease.

Create a file of a given size in linux

If you're trying to create a sparse file, you can use dd by 'skip'ing to the last block instance. ls -ls shows the actual size vs. the reported size

Save all commands from commandlinefu.com to plain text sort by vote

Faster then other method using wget For obtain all commands use $nu=`curl http://www.commandlinefu.com/commands/browse |grep -o "Terminal - All commands -.*results$" | grep -oE "[[:digit:],]{4,}" | sed 's/,//'`; $curl http://www.commandlinefu.com/commands/browse/sort-by-votes/plaintext/[0-"$nu":25] | grep -vE "_curl_|\.com by David" > clf-ALL.txt For more version specific $nu=`curl http://www.commandlinefu.com/commands/browse |grep -o "Terminal - All commands -.*results$" | grep -oE "[[:digit:],]{4,}" | sed 's/,//'`; $curl http://www.commandlinefu.com/commands/browse/sort-by-votes/plaintext/[0-"$nu":25] | grep -vE "_curl_|\.com by David" > clf-ALL_"$nu".txt Also download dirctly from my dropbox My drop box invitaion link is http://db.tt/sRdJWvQq . Use it and get free 2.5 GB space.

display systemd log entries for sshd using "no-pager" (a bit like in pre-systemd: grep sshd /var/log/messages)

In pre-systemd systems, something like: "# grep sshd /var/log/messages" would display log events in /var/log/messages containing "sshd". # journalctl -u sshd --no-pager The above command displays similar results for systemd systems. (Note that this needs to be run with root permissions to access the log data.)

Define shell variable HISTIGNORE so that comments (lines starting with #) appear in shell history

I was surprised to find that with RedHat bash, I could not find any comment lines (begining with #) in my bash shell history. Surprised because in Mageia Linux this works. It turns out that RedHat's bash will keep comment lines if in my .bashrc, I define: export HISTIGNORE=' cd "`*: PROMPT_COMMAND=?*?' Why have comment lines in shell history? It's a handy and convenient way to make proto-commands (to be completed later) and for storing brief text data that is searchable in shell history.

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