pages:howtos:bash:bash-command-line-tricks
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| pages:howtos:bash:bash-command-line-tricks [2021/02/10 20:00] – created mischerh | pages:howtos:bash:bash-command-line-tricks [2022/11/25 15:09] (current) – [exit terminal but leave all processes running] mischerh | ||
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| What if the separators are something else, like colons : | What if the separators are something else, like colons : | ||
| - | The / | + | ///etc/passwd// is a good example. |
| Just specify the separator with -s parameter like this: | Just specify the separator with -s parameter like this: | ||
| + | <sxh bash; gutter: false> | ||
| cat /etc/passwd | column -t -s : | cat /etc/passwd | column -t -s : | ||
| + | </ | ||
| + | < | ||
| + | root x 0 0 root /root /bin/bash | ||
| + | daemon | ||
| + | bin | ||
| + | sys | ||
| + | sync x 4 65534 sync /bin / | ||
| + | games | ||
| + | man | ||
| + | lp x 7 7 lp / | ||
| + | mail x 8 8 mail / | ||
| + | news x 9 9 news / | ||
| + | uucp x 10 | ||
| + | proxy | ||
| + | backup | ||
| + | list x 38 | ||
| + | gnats | ||
| + | nobody | ||
| + | _apt x 100 65534 / | ||
| + | systemd-timesync | ||
| + | systemd-network | ||
| + | systemd-resolve | ||
| + | messagebus | ||
| + | tss | ||
| + | dnsmasq | ||
| + | usbmux | ||
| + | rtkit | ||
| + | sshd x 109 65534 / | ||
| + | pulse | ||
| + | avahi | ||
| + | saned | ||
| + | colord | ||
| + | geoclue | ||
| + | hplip | ||
| + | sddm x 117 124 Simple Desktop Display Manager | ||
| + | user x 1000 | ||
| + | systemd-coredump | ||
| + | _rpc x 118 65534 / | ||
| + | statd | ||
| + | nvpd x 120 125 NVIDIA Persistence Daemon,,, | ||
| + | uuidd | ||
| + | </ | ||
| - | ~\ownCloud\zim\Bilder\DEF\bash-command-line-tricks\002-users-tabular-view.png | + | ===== Run Until Success |
| - | + | ||
| - | + | ||
| - | + | ||
| - | Run Until Success | + | |
| - | ----------------- | + | |
| If you search google about that trick, you will find a lot of questions about people asking how to repeat the command till it returns success and runs properly, like ping the server till it becomes alive or check if a file with a specific extension is uploaded at specific directory or maybe check if a specific URL becomes available or maybe any geeky thing, the list is very long. | If you search google about that trick, you will find a lot of questions about people asking how to repeat the command till it returns success and runs properly, like ping the server till it becomes alive or check if a file with a specific extension is uploaded at specific directory or maybe check if a specific URL becomes available or maybe any geeky thing, the list is very long. | ||
| You can use the while true loop to achieve that: | You can use the while true loop to achieve that: | ||
| + | <sxh bash> | ||
| + | while true | ||
| + | do | ||
| + | ping -c 1 heise.de > /dev/null 2>&1 && break | ||
| + | done | ||
| + | </ | ||
| - | ~\ownCloud\zim\Bilder\DEF\bash-command-line-tricks\03-repeat-till-success.png | ||
| - | We use > /dev/null 2>& | + | We use //> /dev/null 2>&1// to redirect normal output and errors to ///dev/null//. |
| Actually, this is one of coolest Linux Command Line Tricks for me. | Actually, this is one of coolest Linux Command Line Tricks for me. | ||
| - | Sort Processes by Memory or CPU Usage | + | ===== Sort Processes by Memory or CPU Usage ===== |
| - | ------------------------------------- | + | To sort by memory usage: |
| - | ### To sort by memory usage: | + | <sxh bash; gutter: false> |
| - | ~\ownCloud\zim\Bilder\DEF\bash-command-line-tricks\04-sort-by-memory-usage.png | + | ps aux | sort -nk 4 |
| + | </ | ||
| - | ### To sort by CPU usage: | + | To sort by CPU usage: |
| - | ~\ownCloud\zim\Bilder\DEF\bash-command-line-tricks\05-sort-by-cpu-usage.png | + | < |
| + | ps aux | sort -nk 3 | ||
| + | </ | ||
| - | Check Your Architecture | + | ===== Check Your Architecture |
| - | ----------------------- | + | <sxh bash; gutter: false> |
| getconf LONG_BIT | getconf LONG_BIT | ||
| + | </ | ||
| - | + | ===== Monitor Multiple Log Files Concurrently | |
| - | Monitor Multiple Log Files Concurrently | + | |
| - | --------------------------------------- | + | |
| You can use the tail command to watch your logs and that’s fine, but sometimes you may need to monitor multiple log files simultaneously to take some actions. | You can use the tail command to watch your logs and that’s fine, but sometimes you may need to monitor multiple log files simultaneously to take some actions. | ||
| - | Using multitail command which supports text highlighting, | + | Using **multitail** command which supports text highlighting, |
| - | + | ||
| - | ~\ownCloud\zim\Bilder\DEF\bash-command-line-tricks\06-multitail.png | + | |
| - | + | ||
| - | You can install it if it is not found on your system like this: | + | |
| - | + | ||
| - | apt-get install multitail | + | |
| - | Return to Your Previous Directory | + | ===== Return to Your Previous Directory |
| - | --------------------------------- | + | |
| It’s not a trick but some people forget it, others use it every minute. | It’s not a trick but some people forget it, others use it every minute. | ||
| - | Just type cd – and you will return back to the previous directory. | + | Just type //cd –// and you will return back to the previous directory. |
| + | <sxh bash; gutter: false> | ||
| + | cd – | ||
| + | </ | ||
| + | ===== Make non-interactive as interactive shell session ===== | ||
| + | To do this, put our settings in ~/ | ||
| - | Watch Command Output | + | ===== Watch Command Output |
| - | -------------------- | + | |
| By using watch command, you can watch any output of any command, for example, you can watch the free space and how it is growing: | By using watch command, you can watch any output of any command, for example, you can watch the free space and how it is growing: | ||
| + | <sxh bash; gutter: false> | ||
| watch df –h | watch df –h | ||
| + | </ | ||
| You can imagine what you can do with any variant data that you can watch using watch command. | You can imagine what you can do with any variant data that you can watch using watch command. | ||
| - | + | ===== Run Your Program After Session Killing | |
| - | Run Your Program After Session Killing | + | |
| - | -------------------------------------- | + | |
| When you run any program in the background and close your shell, definitely it will be killed, what about if it continues running after closing the shell. | When you run any program in the background and close your shell, definitely it will be killed, what about if it continues running after closing the shell. | ||
| - | This can be done using the nohup command which stands for no hang up. | + | This can be done using the nohup command which stands for //no hang up//. |
| + | <sxh bash; gutter: false> | ||
| nohup wget site.com/ | nohup wget site.com/ | ||
| + | </ | ||
| This command is really one of the most useful Linux command line tricks for most webmasters. | This command is really one of the most useful Linux command line tricks for most webmasters. | ||
| - | ~\ownCloud\zim\Bilder\DEF\bash-command-line-tricks\07-nohup-command.png | + | A file will be generated in the same directory with the name //nohup.out// contains the output of the running program. |
| - | A file will be generated in the same directory with the name nohup.out contains the output of the running program. | ||
| - | ~\ownCloud\zim\Bilder\DEF\bash-command-line-tricks\08-nohup-output.png | + | ===== Answer bot Using Yes & No Commands ===== |
| - | Cool command right? | ||
| - | |||
| - | |||
| - | Answer bot Using Yes & No Commands | ||
| - | ---------------------------------- | ||
| It’s like an answer bot for those commands whose require the user to say yes. | It’s like an answer bot for those commands whose require the user to say yes. | ||
| That can be done using the yes command: | That can be done using the yes command: | ||
| + | <sxh bash; gutter: false> | ||
| yes | apt-get update | yes | apt-get update | ||
| + | </ | ||
| Or maybe you want to automate saying no instead, this can be done using the following command: | Or maybe you want to automate saying no instead, this can be done using the following command: | ||
| + | <sxh bash; gutter: false> | ||
| yes no | command | yes no | command | ||
| + | </ | ||
| - | + | ===== Create a File With a Specific Size ===== | |
| - | ~\ownCloud\zim\Bilder\DEF\bash-command-line-tricks\09-yes-command.png | + | Use the **dd** command to create a file with a specific size: |
| - | + | <sxh bash; gutter: false> | |
| - | + | ||
| - | Create a File With a Specific Size | + | |
| - | ---------------------------------- | + | |
| - | Use the dd command to create a file with a specific size: | + | |
| dd if=/ | dd if=/ | ||
| + | </ | ||
| This will create a file with 10-megabyte size filled with zeros. | This will create a file with 10-megabyte size filled with zeros. | ||
| + | <sxh bash; gutter: false> | ||
| dd if=/ | dd if=/ | ||
| + | </ | ||
| - | + | ===== Run Last Command as Root ===== | |
| - | + | ||
| - | Run Last Command as Root | + | |
| - | ------------------------ | + | |
| Sometimes you forget to type sudo before your command that requires root privileges to run, you don’t have to rewrite it, just type: | Sometimes you forget to type sudo before your command that requires root privileges to run, you don’t have to rewrite it, just type: | ||
| + | <sxh bash; gutter: false> | ||
| sudo !! | sudo !! | ||
| + | </ | ||
| - | + | ===== Record your Command Line Session | |
| - | ~\ownCloud\zim\Bilder\DEF\bash-command-line-tricks\11-sudo.png | + | If you want to record what you’ve typed in your shell screen, you can use the **script** command which will save all of your typings to a file named typescript. |
| - | + | <sxh bash; gutter: false> | |
| - | + | ||
| - | Record your Command Line Session | + | |
| - | -------------------------------- | + | |
| - | If you want to record what you’ve typed in your shell screen, you can use the script command which will save all of your typings to a file named typescript. | + | |
| script | script | ||
| + | </ | ||
| Once you type exit, all of your commands will be written to that file so you can review them later. | Once you type exit, all of your commands will be written to that file so you can review them later. | ||
| - | Replacing Spaces with Tabs | + | ===== Replacing Spaces with Tabs ===== |
| - | -------------------------- | + | You can replace any character with any other character using **tr** command which is very handy. |
| - | You can replace any character with any other character using tr command which is very handy. | + | <sxh bash; gutter: false> |
| cat geeks.txt | tr ': | cat geeks.txt | tr ': | ||
| + | </ | ||
| This command will replace the spaces with tabs. | This command will replace the spaces with tabs. | ||
| - | ~\ownCloud\zim\Bilder\DEF\bash-command-line-tricks\12-tr-command.png | + | ===== Convert Character Case ===== |
| + | < | ||
| + | cat my_file | tr a-z A-Z > output.txt | ||
| + | </ | ||
| + | This command converts the content of the file to upper case using the tr command. | ||
| - | Convert Character Case | + | ===== Powerful xargs Command ===== |
| - | ---------------------- | + | We can say that **xargs** command is one of the most important Linux command line tricks, you can use this command to pass outputs between commands as arguments, for example, you may search for png files and compress them or do anything with them. |
| + | <sxh bash; gutter: false> | ||
| + | find . -name " | ||
| + | </ | ||
| - | cat my_file | tr a-z A-Z > output.txt | + | Or maybe you have a list of URLs in a file and you want to download them or process them in a different way: |
| + | <sxh bash; gutter: false> | ||
| + | cat links.txt | xargs wget | ||
| + | </ | ||
| + | The **cat** command result is passed to the end of **xargs** command. | ||
| - | This command | + | What if your command |
| + | Just use //{}// combined with //–i// parameter to replace the arguments in the place where the result should go like this: | ||
| + | <sxh bash; gutter: false> | ||
| + | ls /etc/*.conf | xargs -i cp {} ~/tmp/out/ | ||
| + | </ | ||
| - | Powerful xargs Command | + | ===== Redo last command as root===== |
| - | ---------------------- | + | <sxh bash; gutter: false> |
| - | We can say that xargs command is one of the most important Linux command line tricks, you can use this command to pass outputs between commands | + | #as user |
| + | vim / | ||
| + | sudo !! | ||
| + | </ | ||
| - | find . -name "*.png" -type f -print | xargs tar -cvzf pics.tar.gz | + | ===== Keyboard Shortcuts ===== |
| + | | ||
| + | Emacs editing mode key bindings are taken from the text editor Emacs. | ||
| - | Or maybe you have a list of URLs in a file and you want to download them or process them in a different way: | + | On some systems, Esc must be used instead |
| - | cat links.txt | xargs wget | + | * < |
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * Sends an EOF marker, which (unless disabled by an option) closes the current shell (equivalent to the command exit). (Only if there is no text on the current line) | ||
| + | * If there is text on the current line, deletes the current character (then equivalent to the key Delete). | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| + | * < | ||
| - | The cat command result is passed to the end of xargs command. | + | ===== RAMdisk ===== |
| + | <sxh bash; gutter: false> | ||
| + | mkdir -pv /mnt/ram | ||
| + | mount -t tmpfs tmpfs /mnt/ram -o size=8192M | ||
| + | </ | ||
| - | What if your command | + | ===== Prevent |
| + | just type a leading < | ||
| + | <sxh bash; gutter: false> | ||
| + | echo " | ||
| + | ^- this is SPACE | ||
| + | </ | ||
| + | |||
| + | ===== Edit/change last typed command ===== | ||
| + | <sxh bash; gutter: false> | ||
| + | cat / | ||
| + | fc | ||
| + | |||
| + | # or | ||
| + | ^bash^vim | ||
| + | </ | ||
| + | |||
| + | ===== SSH Tunnel ===== | ||
| + | **-N**: Do not execute a remote command. | ||
| + | <sxh bash; gutter: false> | ||
| + | ssl -L < | ||
| - | Just use {} combined with –i parameter | + | # e.g. local port 8080 to remote localhost:80 |
| + | ssl -L 8080: | ||
| + | </ | ||
| - | ls /etc/*.conf | xargs -i cp {} /home/likegeeks/Desktop/out/ | + | ===== Create multiple folders ===== |
| + | <sxh bash; gutter: false> | ||
| + | mkdir -pv /home/user/folder{1, | ||
| + | </sxh> | ||
| + | ===== tee - Intercept STDOUT and log to file===== | ||
| + | <sxh bash; gutter: false> | ||
| + | cat ~/.bashrc | tee -a ~/ | ||
| + | </ | ||
| - | ~\ownCloud\zim\Bilder\DEF\bash-command-line-tricks\13-xargs-command.png | + | ===== exit terminal but leave all processes running ===== |
| + | < | ||
| + | disown | ||
| + | </ | ||
| + | ===== Simultaneously copy a file, change permissions/ | ||
| + | <sxh bash; gutter: false> | ||
| + | install -v -C --mode 0775 --owner < | ||
| + | </ | ||
| + | ---- | ||
| + | ~~DISCUSSION~~ | ||
pages/howtos/bash/bash-command-line-tricks.1612987254.txt.gz · Last modified: 2021/02/10 20:00 by mischerh