Hey,
I would like to share few of my Linux tricks and commands I use in day to day work. I know everyone has own best practices but I hope that maybe some of the following will be useful for you too ;-)
1. rm: cannot remove file: Permission denied
When you executed command but forget about sudo ;-)
$ rm file_to_remove
rm: cannot remove 'file_to_remove': Permission denied
$ sudo !!
sudo rm file_to_remove
!! - repeats the last command in Bash
2. Vim: E212: Can't open file for writing
You get permission error when trying to save recent changes... sounds familiar? Do you know you can use sudo directly from Vim?
:w !sudo tee %
3. ctrl+r, search in bash history
When you run commands in console, Bash save the history in a .bash_history file. If you want to re-run particular command but you don't remember the exact syntax, you can search for it,
ctrl+r
(reverse-i-search)`': part_of_the_command_you_are_searching_for
click ctrl+r again for the next result ;-)
alternative way is running: history | grep part_of_the_command_you_are_searching_for
4. Where to find the ascii table?
Do you know the ascii table is already in manual page?
$ man 7 ascii
5. Config file backup
If you're going to edit any configuration file it's always a good practice to make a backup of the file. Usually we run,
$ cp config.cfg config.cfg.bak
but there is a quicker way ;-)
$ cp config.cfg{,.bak}
6. Back to the previous directory
If you changed the directory to another and want to back to the previous one, you can run
$ cd -
This works because Bash keep the current and previous locations in $PWD and $OLDPWD environment variables.
7. Generate test file with particular size
If you need test file with particular size, you can use dd tool,
$ dd if=/dev/zero of=file count=1024 bs=1M
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 13.2885 s, 80.8 MB/s
- if is the source file/device (/dev/zero is block device which prints "0" characters)
- of is the output file/device name
- count is for the number of blocks we want to write,
- bs is the block size,
8. Delete files older than X...
If you want to delete files older than X days from directory, you can use a tool called find.
$ find /var/log/myapplication/ -type f -mtime +100 -delete
this simple command will remove all files older than 100 days from /var/log/myapplication/.
Please let me know if this is something you would like to read in future and don't forget to share your tricks and commands in comments ;-)
$ logout
Posted on Utopian.io - Rewarding Open Source Contributors