• Useful commands
  • File/folder listing
  • File copy/transfer
  • File operations
  • miscellaneous
• File & Folder compression
  • gzip
  • xz
  • tar
  • zip
• Process Handling
• Linux utilities you should use instead
  • fd: replacement for find
  • exa: replacement for ls
  • gdu: replacement for du
  • fzz: replacement for Ctrl+R(reverse-i-search)
  • bat: replacement for cat
  • Terminal file managers
• Useful bash variables
• Bash color schemes
• Things to do after installing ubuntu

Useful commands

File/folder listing

1. size of the current directory

du -shx

2. size of folders in current directory

du -d1 -h
du -d1 -h | sort -h   # sort according to size

3. list all files with size greater than 1GB (using fd)

fd -S +1G

4. total size of all files named data.dat

fd data.dat -X du -ch
fd -e txt -X du -ch    # files with `txt` extension

5. compress all .txt files with xz

fd -e txt -j 1 -x xz # -j 1 wll launch one instance of `xz`

6. Find multiple patterns with fd

fd '(pattern1|pattern2)'

7. Find exact matches with fd

fd '^pattern$'

8. tree with file size

tree -h -d 1 --du /path/to/dir

File copy/transfer

1. Copy files with progress and speed shown:

rsync -zmavh --progress --stats

2. rsync only copy file with certain extension copy files only with .sh extension

rsync -zarvm --include="*/" --include="*.sh" --exclude="*" "$from" "$to"

3. rsync only transfer certain files
   search the list of files with fd (or find) and send it using rsync

fd <search_pattern> | rsync -avm  --progress --stats --files-from=- . $dst

File operations

1. Replace text in file without opening it

sed -i "s/string/replace/g" file

2. print two file side by side

pr FILE1 FILE2 -m 

3. Print m to n lines of a file:

sed -n 'm,np' file

miscellaneous

1. set date and time directly from terminal:

sudo date -s "$(wget -qSO- --max-redirect=0 google.in 2>&1 | grep Date: | cut -d' ' -f5-8)Z"

2. Check diskIO of processes

sudo iotop

3. use function with xargs

moveRun() {
  cwd=$(pwd)
  cd $1
  pwd
  cd $cwd
}

export -f moveRun
ls -d */ | xargs -n1 bash -c 'moveRun "$@"' _

4. tail with timestamp

tail -f outputfile | xargs -IL date +"%I:%M:%S %p"

5. Quickly benchmark file I/O speed

# clear cache
echo 3 | sudo tee /proc/sys/vm/drop_caches
# write speed
dd if=/dev/zero of=./output conv=fdatasync bs=384k count=1k
# read speed
dd if=./output of=/dev/null bs=384k count=1k
# clear
rm output

6. Check location of some running command

ls -l /proc/<proc_id>/exe

7. Mount remote with sshfs

sshfs user@ip:remote_directory local_directory

8. Wait for a process to finish with PID

tail --pid=$PID -f /dev/null

File & Folder compression

gzip

gzip -kv -6 <filename>
#or
gzip -kvr -6 <directory>

-k : is to keep the original file after generating the compressed one, by default it removes the original file.
-v is for verbose.
-6 is the (default) compression level, available number are from 1 to 9, 1 being the fastest and 9 meaning the best/slowest compression.
For directory -r flag is used for recursive compression.

Decompress the same with

gzip -d file.gz

• Similar to gzip another compression utility bzip2. It has similar flags and usage like gzip
• For parallel gzip use https://zlib.net/pigz/

xz

xz(lzma compression) is better alternative to gzip use it with

xz -k -6 -T 3 --verbose <file>

xz supports parallel processing, use it with -T 3 with 3 being number of processor.

• For best possible compression of large files use lrzip

• A Quick Benchmark: Gzip vs. Bzip2 vs. LZMA

• Which one to use?

  • If you want to quickly compress the file and on a limited resource use gzip.
  • If you want the best compression/ smallest file size and have enough RAM and processor available use xz

tar

tar by itself only archive multiple files or folder into one single file and doesn't compress anything. Then other compression utilities are used to compress the file. Gnu tar can handle this whole process on its own. To compress the sample-folder into archive.tar.gz

tar -zcvf archive.tar.gz sample-folder

-z : Use gzip to compress
-c : Create archive
-v : Verbose
-f : Archive file name
-j : Use bzip2 utility
-J : Use xz utility
-I : Specify compression utility, -I 'gzip -6' is same as -z
To decompress the file into the folder again replace the create (-c) with extract (-x) flag

tar -xvf archive.tar.gz

To list the contents of a compressed file use:

tar -tf file.tar.gz

zip

zip output.zip [filename] [-r folder_name]

to unzip use

unzip file.zip [-d destination_folder]

Process Handling

Command	Description
Ctrl+C	Kill the current forground processs. (Send SIGINT signale to the process)
Ctrl+Z	Suspend the current forground processs. (Send SIGSTOP signale to the process)
kill <pid>	Send signall to a process. Default is SIGTERM. Use kill -l to check the full list of available signal
pkill <name>	Kill all processes with name "name"
fg	Move jobs to foreground
bg	Move jobs to background
jobs -l	List all background jobs for the current shell.
pgrep -la <name> top -bc -n1 | grep <name>	List all jobs with name "name"

Linux utilities you should use instead

Better and faster alternative to regularly use bash commands

fd: replacement for find

Install with sudo apt install fd-find or download the latest release from https://github.com/sharkdp/fd
Preferred usage fd (part of) file_name [-e extension] [-S size_specs] [-x executable {}] [-t d/f] [-E exclude]

---

exa: replacement for ls

Download latest release from https://github.com/ogham/exa
Preferred usage exa -l -T -L <depth> --no-user

---

gdu: replacement for du

Install gdu from https://github.com/dundee/gdu#installation. Preferred usage gdu

---

fzz: replacement for Ctrl+R(reverse-i-search)

Install with git clone --depth 1 https://github.com/junegunn/fzf.git ~/.fzf && ~/.fzf/install
Now source the ~/.bashrc and it will replace the Ctrl+R, bash reverse with fzf

---

bat: replacement for cat

Download it from https://github.com/sharkdp/bat

---

Terminal file managers

1. lf: https://github.com/gokcehan/lf
2. ranger: https://github.com/ranger/ranger
3. nnn: https://github.com/jarun/nnn

Useful bash variables

• $1, $2, $3, ... are the positional parameters.
• "$@" is an array-like construct of all positional parameters, {$1, $2, $3 ...}.
• "$*" is the IFS expansion of all positional parameters, $1 $2 $3 ....
• $# is the number of positional parameters.
• $- current options set for the shell.
• $$ pid of the current shell (not subshell).
• $_ most recent parameter (or the abs path of the command to start the current shell immediately after startup).
• $IFS is the (input) field separator.
• $? is the most recent foreground pipeline exit status.
• $! is the PID of the most recent background command.
• $0 is the name of the shell or shell script.

Most of the above can be found under Special Parameters in the Bash Reference Manual. There are all the environment variables set by the shell.

Bash color schemes

# Reset
Color_Off='\033[0m'       # Text Reset

# Regular Colors
Black='\033[0;30m'        # Black
Red='\033[0;31m'          # Red
Green='\033[0;32m'        # Green
Yellow='\033[0;33m'       # Yellow
Blue='\033[0;34m'         # Blue
Purple='\033[0;35m'       # Purple
Cyan='\033[0;36m'         # Cyan
White='\033[0;37m'        # White

# Bold
BBlack='\033[1;30m'       # Black
BRed='\033[1;31m'         # Red
BGreen='\033[1;32m'       # Green
BYellow='\033[1;33m'      # Yellow
BBlue='\033[1;34m'        # Blue
BPurple='\033[1;35m'      # Purple
BCyan='\033[1;36m'        # Cyan
BWhite='\033[1;37m'       # White

# Underline
UBlack='\033[4;30m'       # Black
URed='\033[4;31m'         # Red
UGreen='\033[4;32m'       # Green
UYellow='\033[4;33m'      # Yellow
UBlue='\033[4;34m'        # Blue
UPurple='\033[4;35m'      # Purple
UCyan='\033[4;36m'        # Cyan
UWhite='\033[4;37m'       # White

# Background
On_Black='\033[40m'       # Black
On_Red='\033[41m'         # Red
On_Green='\033[42m'       # Green
On_Yellow='\033[43m'      # Yellow
On_Blue='\033[44m'        # Blue
On_Purple='\033[45m'      # Purple
On_Cyan='\033[46m'        # Cyan
On_White='\033[47m'       # White

# High Intensity
IBlack='\033[0;90m'       # Black
IRed='\033[0;91m'         # Red
IGreen='\033[0;92m'       # Green
IYellow='\033[0;93m'      # Yellow
IBlue='\033[0;94m'        # Blue
IPurple='\033[0;95m'      # Purple
ICyan='\033[0;96m'        # Cyan
IWhite='\033[0;97m'       # White

# Bold High Intensity
BIBlack='\033[1;90m'      # Black
BIRed='\033[1;91m'        # Red
BIGreen='\033[1;92m'      # Green
BIYellow='\033[1;93m'     # Yellow
BIBlue='\033[1;94m'       # Blue
BIPurple='\033[1;95m'     # Purple
BICyan='\033[1;96m'       # Cyan
BIWhite='\033[1;97m'      # White

# High Intensity backgrounds
On_IBlack='\033[0;100m'   # Black
On_IRed='\033[0;101m'     # Red
On_IGreen='\033[0;102m'   # Green
On_IYellow='\033[0;103m'  # Yellow
On_IBlue='\033[0;104m'    # Blue
On_IPurple='\033[0;105m'  # Purple
On_ICyan='\033[0;106m'    # Cyan
On_IWhite='\033[0;107m'   # White

For a comprehensive index, please see the Reference Manual Variable Index.
Reference : StackOverflow

Things to do after installing ubuntu

• Things to do after installing ubuntu