LQ Poll: What's your favorite Linux terminal trick?

Lucio Chiappetti · 05-20-2019, 03:51 AM

If by terminal you mean terminal emulator like xterm or urxvt, the most useful is an "identframe" script which annotates thew window banner with hostname, username and tty numbere. This is invoked by .cshrc on all our machines (so when one ssh's there, one knows where one is, and is "invoked back" exiting by aliases like ssh !* ; identframe). I attach the version I am using (with escape sequences for a lot of old obsoleted terminals).

Otherwise I have plenty of aliases in my .cshrc.

mastemmer · 05-20-2019, 07:31 PM

Search a searchdir looking for files that have a substring in their name
du -a searchdir | grep substring

slow_footed_Buffalo · 05-20-2019, 07:37 PM

for the common idiot spect is great sorry if you dont know what Im talking about. probably WP devs

kysh · 05-21-2019, 07:56 AM

watch du -sh "'Directory when doing space intensive file operations'"

rhamel · 05-23-2019, 04:55 AM

Over the years, I have tried several ways to find more space on filesystems which, just inevitably, seem to fill up over time.

It was always a pain until I discovered ncdu. This is a little utility which does one thing and does it well.

ncdu sorts files & directories by size, biggest first.

It then allows you to delete the file/folder using a simple highlight bar and pressing the letter 'd'. You then get a confirmation dialog (in case you pressed 'd' accidentally).

There is the ability to invoke a shell if you need to examine the contents of the file first.

This utility, ncdu has become my absolute must-have command for managing filesystem space.

As the saying goes, "Never leave home without it!"

rhamel · 05-23-2019, 10:54 AM

Over the years, I have tried several ways to find more space on filesystems which, just inevitably, seem to fill up over time.

It was always a pain until I discovered ncdu. This is a little utility which does one thing and does it well.

ncdu sorts files & directories by size, biggest first.

It then allows you to delete the file/folder using a simple highlight bar and pressing the letter 'd'. You then get a confirmation dialog (in case you pressed 'd' accidentally).

There is the ability to invoke a shell if you need to examine the contents of the file first.

This utility, ncdu has become my absolute must-have command for managing filesystem space.

As the saying goes, "Never leave home without it!"

WideOpenSkies · 05-24-2019, 10:33 AM

Quote:

Originally Posted by rhamel

Over the years, I have tried several ways to find more space on filesystems which, just inevitably, seem to fill up over time.

It was always a pain until I discovered ncdu. This is a little utility which does one thing and does it well.

ncdu sorts files & directories by size, biggest first.

It then allows you to delete the file/folder using a simple highlight bar and pressing the letter 'd'. You then get a confirmation dialog (in case you pressed 'd' accidentally).

There is the ability to invoke a shell if you need to examine the contents of the file first.

This utility, ncdu has become my absolute must-have command for managing filesystem space.

As the saying goes, "Never leave home without it!"

This is great. Thank you!

josephj · 05-25-2019, 01:13 AM

It took me forever to start using Alt+. which inserts the last argument of the previous command, but now I use it all the time.

proMusic · 05-25-2019, 03:17 AM

Code:

poweroff

Just Kidding!

Code:

alias h='history|grep'

^ I frequently find this alias useful for searching my history.

Code:

man manpage | col -b -x > somefile

^ Turn a manpage into a text file, which I use as part of a script to grep keywords in my manpages.

bodiccea · 05-25-2019, 05:26 AM

The following is not a terminal trick, but rather a system/keyboard one.

REISUB. Remember this word, it could save you when your system becomes really unstable/unresponsive, and your only solution is the power-off button.

First, the following will not work if the system is not configured properly: You need to to have the "magic system request key" enabled (more details on https://www.kernel.org/doc/html/late...ide/sysrq.html):

This means you need to add the following line to your /etc/sysctl.conf:

Code:

kernel.sysrq=244

You will need to to reboot to have this effective (or you may avoid a reboot by enabling it with (as root): echo 244 > /proc/sys/kernel/sysrq).

Then, the magic can operate: In case of fatal system issues that you cannot solve another way, instead of a brutal power-off, just hold the <alt> and <sysrq> keys, then, in sequence, press the 'R', 'E', 'I', 'S', 'U', and 'B' keys.

The actions will be the following:

R: switch keyboard to XLATE (ASCII) mode.
E: send SIGTERM signal to all processes (except init). Should allow (well written) processes to exit a clean way (save files, etc...)
I: send SIGKILL signal to all processes (except init). Data not saved in previous step will be lost
S: write all caches data to disk (will reduce risk of data corruption)
U: remount all mounted filesystems read-only
B: reboot

You should wait between each key, to give the system enough time to execute the operations.

teckk · 05-25-2019, 06:44 AM

A few examples of man page to different format.

Code:

man -t ls | ps2pdf - output.pdf
man ls | roff2pdf > output.pdf

man -P cat ls > output.txt
man ls | roff2text > output.txt
man ls | col -b > output.txt
man -t ls | ps2ascii - output.txt

man ls | roff2html > output.html
man ls | groff -mandoc -Thtml > output.html

teckk · 05-25-2019, 07:43 AM

List all commands present on system by folder.

Code:

ls ${PATH//:/ }

And of course you can redirect that to file

Code:

ls ${PATH//:/ } > com.txt

Another one

Code:

apropos --sections 1,8 -w '*' | less

hydrurga · 05-25-2019, 07:47 AM

Quote:

Originally Posted by teckk

List all commands present on system by folder.

Code:

ls ${PATH//:/ }

Sweet.

individual · 05-25-2019, 10:02 AM

Quote:

Originally Posted by mastemmer

Search a searchdir looking for files that have a substring in their name
du -a searchdir | grep substring

find dir -name '*substring*' might be more appropriate for this use case.

average_user · 05-25-2019, 11:41 AM

Quote:

Originally Posted by teckk

List all commands present on system by folder.

Code:

ls ${PATH//:/ }

In Bash you can achieve something similar with `compgen -c` but it will just list all possible commands without directories names.