Lpic-1 101

Front 1

exec

Back 1

Runs a program that replaces the current shell. When the program terminates, it's as if you terminated the shell.

Front 2

time

Back 2

Times how long a command takes to execute. Displays total execution time, CPU time, and system CPU time.

Front 3

pwd

Back 3

print working directory

Front 4

history

Back 4

~/.bash_history keeps a record of every command you type. Use up and down arrows to review your command history.

-c clears the history

Front 5

mkdir

Back 5

Creates a directory.

-p create parent directories as well

Front 6

touch

Back 6

Update the access and modification times of each file named. Creates an empty file if file doesn't exist.

example: touch file1 file2 file3

Front 7

ls

Back 7

List files.

-l include file type, permissions user:group, bytes, and date modified

-a include hidden files

Front 8

bash configuration files

Back 8

/etc/profile
/etc/bash.bashrc
~/.profile
~/.bashrc

.profile system-wide settings, typically configures PATH and other environment variables.

.bashrc settings for login shells, typically includes command aliases and umask settings

Front 9

env

Back 9

display environment variables

Front 10

Standard input
Standard output
Standard error

Back 10

> creates/overwrites stdout to file
>> creates/appends stdout to file
2> creates/overwrites stderr to file
2>> appends/overwrites stderr to file
&> creates/overwrites stdout and stderr to file
< redirect stdin from file
| pipes stdout from one program to stdin on another

redirecting to /dev/null discards output

Front 11

tee

Back 11

Read from standard output and write to standard output and files.

-a append to given files

Front 12

xargs

Back 12

xarg [options] command

Runs command for every word passed on standard input.

Front 13

find

Back 13

find [options] [expression]

Find files. Use * for glob searches.

-name [pattern] find by name
-iname [pattern] case insensitive
-user [username] files owed by user
-nouser files unknown user
-nogroup files unknow group
-perm [mode] files with mode permissions
-type [filetype] d for directory, f for regular file, s for socket, p for pipe

Front 14

cat

Back 14

Concatenate files to stdout

-n adds line numbers
-b only adds line numbers to nonblank lines
-v displays control characters

Front 15

tac

Back 15

Same as cat but reverses the order of lines.

Front 16

join

Back 16

Join two files by matching contents of specified fields. Requires same ordering of lines, which can be done by sort.

-1 [fieldnum] join on file 1 field number fieldnum

-2 [fieldnum] join on file 2 field number fieldnum

-i ignore case
-t [char] use char as separator

Front 17

paste

Back 17

Merges files line by line.

Front 18

expand

Back 18

Convert tabs to spaces.

-t [num] num number of spaces for each tab

Front 19

unexpand

Back 19

Convert spaces to tabs.

-t [num] num number of spaces for each tab

Front 20

od

Back 20

Display file in octal.

-x display in hex

Front 21

sort

Back 21

Sort file.

-f ignore case
-n sort by number
-r reverse sort
-k [num] sort by num field first

Front 22

split

Back 22

Split a file into two or more files.

-b [size] split files into size bytes
-l [num] split files into num lines

Front 23

uniq

Back 23

Remove adjacent duplicate lines. You can use sort to remove all duplicates.

example: sort duplicates.txt | uniq > deduped.txt

Front 24

tr

Back 24

tr [options] [set1] [set2]

Translate file set1 to set2.

-d delete from file

example1: tr -d '\r' file.txt
deletes carrage returns from file

example2: tr "[:upper:]" "[:lower]" file.txt
translates uppercase to lowercase

example3: tr "[a-z]" "[A-Z]" file.txt
translates lowercase to uppercase

Front 25

Split a file into 2000 byte files.

Back 25

split -b 2000

Front 26

Split a large file into 20 line files.

Back 26

split -l 20

Front 27

Sort a file.txt by it's third field, space separated.

Back 27

sort -k 3 file.txt

Front 28

Do a case insensitive join on field 3 from file1.txt and field 2 from file2.txt using comma as field separator.

Back 28

join -i -t "," -1 3 -2 2 file1.txt file2.txt

Front 29

Concatenate file1.txt and file2.txt into combined.txt

Back 29

cat file1.txt file2.txt > combined.txt

Front 30

In the current directory list all hidden directories starting with kde.

Back 30

find ./ -type d -iname ".kde*"

Front 31

Find all the temporary files in the current directory and remove them.

Back 31

find ./ -name "*~" | xargs rm

Front 32

Display and save a list of files in the current directory to dirlist.txt

Back 32

ls -l | tee dirlist.txt

Front 33

Find the debian package the command mkfs belongs to.

Back 33

dpkg -S `which mkfs`

Front 34

yum configuration files

Back 34

/etc/yum.conf
/etc/yum.repos.d/

Front 35

Create a cpio archive of files in the current directory.

Back 35

ls | cpio -ov > archive.cpio

Front 36

Extract archive.cpio to currect directory, overwriting any existing files and creating any needed directories

Back 36

cpio -iduv < archive.cpio

Front 37

uptime

Back 37

Display the current time, how long the system has been running, how many users are currently loggon on, and the system load averages for the last 1, 5, and 15 minutes.

Front 38

fmt

Back 38

Format long lines of text to 75 characters

-w [num] set width to num characters

Front 39

Install binary-tarball.tar.gz in debian, adding all the files to the package management database.

Back 39

alien --install binary-tarball.tar.gz

Front 40

Number all non blank lines of file.txt

Back 40

nl file.txt
cat -b file.txt

Front 41

pr

Back 41

Prepare text file for printing. Format to 80 character line width. Add page header with current date and time, original filename, and page number.

Front 42

head

Back 42

Print first 10 lines of each file.

-c [num] print num bytes
-n [num] print num lines

Front 43

tail

Back 43

Print last 10 lines of file.

-c [num] print num of bytes
-n [num] print num lines
-f [filename] ouput appended data as file grows

Front 44

Display the last ten lines of /var/log/dmesg and view data as it's appended.

Back 44

tail -f /var/log/dmesg

Front 45

wc

Back 45

Print newline, word, and byte counts.

-l print line count only
-c print byte count only
-w print word count only

Front 46

dpkg-reconfigure

Back 46

Reconfigure an installed debian package.

Front 47

nice

Back 47

Run a process with high or low priority, -20 highest to 19 lowest.

Front 48

renice

Back 48

Change a running process's priority higer or lower, highest -20 to lowest 19.

Front 49

Change all processes owned by user1 and user2 to a priority of 6.

Back 49

renice +6 -u user1 user2

Front 50

Change process to priority -5 for PID1 and PID2

Back 50

renice -5 -p PID1 PID2

Front 51

kill

Back 51

Send signal to process.

Front 52

killall

Back 52

Kill all instances of a program.

-i prompt for each process
-s, --signal [SIGNAL] send SIGNAL to each process

Front 53

lspci

Back 53

List PCI devices.

-v verbosity (-vv, -vvv)
-t tree view