Bash Basics

8/6/2019 Bash Basics

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BASH Basics

Keyboard Use

ctrl+a move cursor to beginning of line

ctrl+c end running program

ctrl+d exit or logout

ctrl+e move cursor to end of line

ctrl+h backspacectrl+l clear screen

ctrl+r search back through command

ctrl+z suspend a program (not ending a program as ctrl-c)

left/right arrows move the cursor

up/down arrows browse through command history

shift+page up browse forward through terminal buffer

shift+page down browse back through terminal buffer

tab command/file name completion

tab+tab command/file name completion possibilities


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Command

--help

apropos

cat

cd

cp date

diff

dos2unix

echo

exit/logout

file

grep

head -x

help

history

ignore errrors

info locate

ls -

man

mkdir

more / less

mv

passwd

pwd

rm

rmdir

set

sort tail -x

touch

uname

uniq

unix2dos

uptime

w / who / finger

whereis

which

whoami/who am I


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BASH Basics

Explanation

display list of options for the command

search a database of command descriptions for pattern / to use when can't remember a command

display the contents of a file

change current working directory / "cd -" toggles between two directories

copy file and directories - cp ~/* ./copies -rvdisplay systems date and time on stdout

compare fn1 to fn2 display on stdout the lines that differ

convert text file to Linux format

display text on stdout

end the bash session

display the type of the file

search for pattern in file

display on stdout the first x lines of file (default 10)

2>/dev/null

help files (info info for help on info)search a database of file system information for cmd

display a listing of the directory or file some options: r=reverse a=all R=recurse l=long

help files (man man for help on man) / q = quit / space bar = forward / b = backwards / "/ string" = search / n = next str

create a new directory

display on stdout one screen at a time / space bar = page forward / b = page backwards / q = quit / "/string" = search

rename / move fn1 to fn2 or rename and move at the same time fn1 fn2

change password of the current user

display current working directory (print working directory)

delete a file or directory - Ex: "rm * -r /" Ex2: rm * -rf = delete recursively and forces the deletion - so it won't ask for co

delete an empty directory

display environment variables

sort then display file on stdoutdisplay on stdout the last x lines of file (default 10)

update the time stamp / create a file if it doesn't exist / syntax = touch filename

display system information

remove adjacent duplicate lines from file then display on stdout

convert text file to Windows format

display how long system has been running

show logged on users

search standard Linux directories for cmd

search the directories in the environment variable PATH for cmd

display on stdout current effective userid

display help for bash builtin commands (help alone lists all)

display command history - !number


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Command Option

ls

Syntax: ls [options] [file] [directory] ls -l /etc

ls -a "-a"

ls -h "-h"

ls -l "-l"

ls -r "-r"

ls -R "-R"

ls -s "-s"

ls -S "-S"

ls -t "-t"

Examples

ls -l /etc

ls -l /home/rich/www

ls -al /home

ls -ash

ls -lash "-lash"


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Description

List directory contents

The ls command will list the files and directories within the current working directory (the directory you are currently in

A file or directory can be specified - wildcards like * can be use to refer to several files.

will show you ALL the files in the directory, including hidden files

will show the size in "human readable format" (ie: 4K, 16M, 1G etc). Must be use in conjunction with the -s option.

reverse order while sorting

will the subdirectories recursively, which means it will show ALL the directories and files within the specified directory.

will also show you the size of the files (in blocks, not bytes)

sorts by file size

sorts by modification time

Lists ALL the files and directories in the /home directory, in the long listing format.

long listing sorted by name including all files (including hidden files) and shows the file size in human readable format

which will give you a long listing format (which shows more info than just the file names - the owner, size, date last mosorts by name

Lists ALL the files in the current directory (no directory was specified so it lists the contents of the current directory),and the size of the files/directories, written in 'human readable' format.


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Command

find / -name filename

find - name "FileName.filenAme"

find -size 100k

find -size +100kfind -size -100k

find -empty -type -f

find -iname "filename"

find -inum [inode number]

find -maxdepth 2 -name filename

find / -maxdepth 3 -name filename

find -mindepth 3 -maxdepth 5 -name f

find -maxdepth 1 -not -iname "pattern

find ~ -empty

find . -maxdepth 1 -empty

find -type s

find -type d

find -type f

find . -type f -name ".*"

find -type d -name ".*"

find -nouser

find -user root -o -user www-data

find -not -user www-data

find -user www-data -not -size +100k

find -atime

find -mtime

find -ctime

find -mtime +2

find -mtime +2 -mtime -5

find also has the -amin, -cmin, and -m

find -name filename

find -group groupname.


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Explanation (default action)

find file under all sub-directories starting from root directory.

use " " to search by filename exactly as specified

find files that are 100k in size

return any files larger than 100kreturn anything smaller.

find files that are empty (-type -f so find does not include directories as empty files)

Find Files Using Name and Ignoring Case

Finding Files by its inode Number

Find file under root and one level down. (i.e root level 1, and one sub-directory level 2

Find file under root and two levels down. (i.e root level 1, and two sub-directories leve

Find file between sub-directory level 2 and 4

Shows the files or directories whose name are not pattern only under current directory

Find all empty files (zero byte file) in your home directory and its subdirectory

List all the empty files only in your working directory.

Find only the socket files

Find all directories and subdirectories in the current working directory

Find only the normal files in the current working directory and subdirectories

Find all the hidden files

Find all the hidden directories

find files without ownership

find all files that are owned by root or by www-data

search for all files owned by a user that are not larger than a certain size

search for all files owned by a group

Search by access time

Search by last time file was modified

Search by last time it was changed

look for any files that have not been modified in the last two days

Two or more days ago, but not more than five days ago.

work with minutes instead of days.

find will display the location of the file or files that match that name

find all files that aren'towned by a user


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Command

grep [pattern] filenamegrep "literal_string" filename

grep "string" FILE_PATTERN

grep [pattern] -w

grep ["pattern pattern"]

grep [pattern] -i

grep -i "string" FILEgrep -iw "is" demo_file

grep [pattern] -v

grep -v "go" demo_text

grep -v -e "pattern" -e "pattern"

grep [pattern] -r

grep -r "ramesh" *

grep [pattern] -c

grep -c "pattern" filename

grep -c this demo_filegrep -v -c this demo_file

grep -l this demo_*

grep -o "is.*line" demo_file

grep -o -b "pattern" file

grep -n "go" demo_text

^ (Caret)

$ (Question)

\ (Back Slash)

[ ] (Brackets)

[^ ]

. (Period)* (Asterisk)

\{x,y\}

\{x\}

\{x,\}

Examples:

grep -I -w [pattern] *

grep smug files

grep '^smug' files

grep 'smug$' files

grep '^smug$' files

grep '\^s' filesgrep '[Ss]mug' files

grep 'B[oO][bB]' files

grep '^$' files

grep '[0-9][0-9]' file

grep b.b

grep '^From: ' /usr/mail/$USER

grep '[a-zA-Z]'

grep '[^a-zA-Z0-9]

grep '[0-9]\{3\}-[0-9]\{4\}'


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grep '^.$'

grep '"smug"'

grep '"*smug"*'

grep '^\.'

grep '^\.[a-z][a-z]'


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searches filename for pattern anywhere in a lineSearch for the given string in a single file

Checking for the given string in multiple files

searches for a whole word

use "pattern" to search for strings including spaces and special characters

ignore case while searching - grep is case sensitive

Case insensitive search using grep -iChecking for full words, not for sub-strings using grep -w

display the lines that do not match the specified pattern / searches for everything except the keyword provided

Invert match using grep -v

display the lines which does not matches all the given pattern.

searches in all files recursively (whole tree)

Searching in all files recursively using grep -r

count maches of whatever pattern

Counting the number of matches using grep -c

find out how many lines matches the patternfind out how many lines that does not match the pattern

Display only the file names which matches the given pattern using grep

Show only the matched string

Show the position of match in the line

Show line number while displaying the output using grep -n

match expression at the start of a line, as in ^A

match expression at the end of a line, as in A$

turn off the special meaning of the next character, as in \^

match any one of the enclosed characters, use Hyphen "-" for a range, as in [0-9]

match any one character except those enclosed in [ ], as in [^0-9]

match a single character of any value, except end of linematch zero or more of the preceding character or expression

match x to y occurrences of the preceding

match exactly x occurrences of the preceding

match x or more occurrences of the preceding

searches files in the current working directory for pattern in any case

{search files for lines with 'smug'}

{'smug' at the start of a line}

{'smug' at the end of a line}

{lines starting with '^s', "\" escapes the ^}{search for 'Smug' or 'smug'}

{search for BOB, Bob, BOb or BoB }

{search for blank lines}

{search for pairs of numeric digits}

search for "bob", "bib", "b-b"

{list your mail}

{any line with at least one letter}

{anything not a letter or number}

{999-9999, like phone numbers}

{lines containing only 'smug'}


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{lines with exactly one character}

{'smug' within double quotes}

{'smug', with or without quotes}

{any line that starts with a Period "."}

{line start with "." and 2 lc letters}


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Command

compress zcat

uncompress

gzip gz

gunzip gz

bzip2 bz2

bzcat bz2

bunzip2 bz2

zip zip

unzip zip

tar -f

tar -f tar

tar -jf / tar-f --bzip tbz2

tar -zf / tar-f --gzip tgz

tar -zf / tar-f --compress tZOptions:

-c / -- create

-t / --list

-x / --extract

-v / --verbose

Examples:

tar -cf filename.

tar -cf file.tar file1 file2 file3

tar -czf file.tgz file1 file2 file3

tar -cjf file.tbz2 file1 file2 file3

tar -tjf file.tbz2tar -xzf file.tgz

Note:

file

Extension


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compress filesview content of file zipped with compress

decompress files

compress filename into .gz files

decompress .gz files

compress filename into bz2 file

view content of file zipped with compress or gzip

decompress files

compress filename into zip file

decompress files

package together - no compression

compress using bzip2

compress using gzip

compress using compress

create

list

extract

verbose

create an archive containing 3 files

same archive compressed using gzip algorithm

same archive compressed using bzip2 algorithm

list the contents of the bzip2 tar ballextract the contents of the gzip tar ball

will tell compression utility used

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Bash Basics