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Commands by tyzbit from sorted by
Terminal - Commands by tyzbit - 8 results
[command] 2> >(fb=$(dd bs=1 count=1 2>/dev/null | od -t o1 -A n); [ "$fb" ] && err=$(printf "\\${fb# }"; cat) && echo "ERROR - $err")
2017-10-16 22:22:42
User: tyzbit
Functions: dd echo od printf
0

This is a bit of a bash hack to catch STDERR and append a log level to it.

So for example, if your script has pseudo loglevels like so:

echo "INFO - finding files"

[ -f ${files} ] || echo "WARN - no files found"

Any subcommands that write to STDERR will screw that up

Adding 2> >(fb=$(dd bs=1 count=1 2>/dev/null | od -t o1 -A n); [ "$fb" ] && err=$(printf "\\${fb# }"; cat) && echo "ERROR - $err") to the command does the following:

2>

Redirect STDERR

>(

Spawn a subshell (STDERR is then redirected to the file descriptor for this subshell)

fb=$(....)

get the first byte of input

[ "$fb" ]

test if there's a first byte

&& err=$(printf....)

save the output to the $err variable

&& echo "ERROR - $err"

append your pseudo loglevel and the error message

Heavily borrowed from https://unix.stackexchange.com/questions/33049/check-if-pipe-is-empty-and-run-a-command-on-the-data-if-it-isnt

exec 5<>/dev/tcp/time.nist.gov/13; cat <&5 & cat >&5; exec 5>&-
2015-07-30 21:12:38
User: tyzbit
Functions: cat exec
Tags: bash Linux unix
15

Ever needed to test firewalls but didn't have netcat, telnet or even FTP?

Enter /dev/tcp, your new best friend. /dev/tcp/(hostname)/(port) is a bash builtin that bash can use to open connections to TCP and UDP ports.

This one-liner opens a connection on a port to a server and lets you read and write to it from the terminal.

How it works:

First, exec sets up a redirect for /dev/tcp/$server/$port to file descriptor 5.

Then, as per some excellent feedback from @flatcap, we launch a redirect from file descriptor 5 to STDOUT and send that to the background (which is what causes the PID to be printed when the commands are run), and then redirect STDIN to file descriptor 5 with the second cat.

Finally, when the second cat dies (the connection is closed), we clean up the file descriptor with 'exec 5>&-'.

It can be used to test FTP, HTTP, NTP, or can connect to netcat listening on a port (makes for a simple chat client!)

Replace /tcp/ with /udp/ to use UDP instead.

\[command]
2015-01-15 18:31:50
User: tyzbit
1

Most distributions alias cp to 'cp -i', which means when you attempt to copy into a directory that already contains the file, cp will prompt to overwrite. A great default to have, but when you mean to overwrite thousands of files, you don't want to sit there hitting [y] then [enter] thousands of times.

Enter the backslash. It runs the command unaliased, so as in the example, cp will happily overwrite existing files much in the way mv works.

tail -f access_log | awk '{print $1 , $12}'
2014-12-24 14:15:52
User: tyzbit
Functions: awk tail
0

Use this command to watch apache access logs in real time to see what pages are getting hit.

for USER in /var/spool/cron/*; do echo "--- crontab for $USER ---"; cat "$USER"; done
2014-12-11 19:48:46
User: tyzbit
Functions: cat echo
0

This is not exhaustive but after checking /etc/cron* is a good way to see if there are any other jobs any users may have set.

Note: this is a repost from a comment "flatcap" made on http://www.commandlinefu.com/commands/view/3726/print-crontab-entries-for-all-the-users-that-actually-have-a-crontab#comment, for which I am grateful and I take no credit.

while sleep 1; do if [ $(echo "$(cat /proc/loadavg | cut -d' ' -f1) > .8 " | bc) -gt 0 ]; then echo -e "\n\a"$(date)" \e[5m"$(cat /proc/loadavg)"\e[0m"; ps aux --sort=-%cpu|head -n 5; fi; done
2014-12-08 15:44:40
User: tyzbit
Functions: cat echo head ps sleep
0

This checks the system load every second and if it's over a certain threshold (.8 in this example), it spits out the date, system loads and top 4 processes sorted by CPU.

Additionally, the \a in the first echo creates an audible bell.

wakeonlan 00:00:DE:AD:BE:EF
2014-06-13 16:16:33
User: tyzbit
0

Wakes up a computer on your LAN with a Wake-On-LAN packet. MAC Address must match the NIC MAC, computer must have WOL enabled in the BIOS.

cvlc /path/to/file.avi -V caca
2014-06-13 16:10:36
User: tyzbit
Tags: video vlc
0

Use this command to watch video files on the terminal using VLC.

prerequisite: VLC and cvlc

sudo apt-get install vlc cvlc