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35 Cards in this Set
- Front
- Back
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who command options |
whoami - see which acct you are using am I - info about your session H- show column headings u- show idle time for each user q- quick list of logged in users b- verify when the system was last booted |
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The /bin Directory |
-Contains binaries, or executables -Programs needed to start the system and perform other essential system tasks -Holds many programs that all users need to work with UNIX/Linux |
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The /sbin Directory |
-Reserved for the system administrator Stores: –Programs that start the system –Programs needed for file system repair –Essential network programs |
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The /boot Directory |
Normally contains: –Files needed by the bootstrap loader •The bootstrap loader is the utility that starts the OS |
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The /dev Directory |
Files here reference system devices (i/o, etc) |
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ls– l |
Use ls–l to see the device type |
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The /etc Directory |
Contains configuration files that the system uses when the computer starts |
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The /home Directory |
Used to offer disk space for users, such as on a system that has multiple user accounts |
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The /root Directory |
Home directory for the root user (system admin) |
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The /mnt Directory |
mounting info, points |
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The /media Directory |
In newer distributions of UNIX/Linux, mount points for removable storage are in /media |
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The /tmp Directory |
Many programs need a temporary place to store data during processing cycles - /tmp |
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mount command |
-t - specify a filesystem to mount |
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pwd |
"print working directory" |
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chmod |
changes file permissions |
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Use > and >> to |
redirect output. |
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Use < and << |
redirect input |
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Two simple ways to create files: |
> accountsfile
touch accountsfile2 |
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touch [ -option] (filename) |
options -a: updates the access time only -m: updates the last time the file was modified -c: prevents the touch command from creating a file if it does not already exist |
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rm |
removes a file -i: displays a warning prompt before file deletion -r: recursively deletes files and directories (CAREFUL!!) |
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rmdir |
removes an EMPTY directory |
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cp |
-i: provides a warning -s: creates a symbolic link -u: prevents cp from copying over a newer existing file |
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mv |
moves a file -i: prompts before overwriting a file with the same name -u: overwrites destination file if the source file is newer than the one in the destination |
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cat |
used to combine files |
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paste |
combines the contents of a file to the screen or to a file
-d: enables you to specify a different seperator (other than tab) between columns -s: causes files to be pasted one after the other instead of in parallel |
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sort |
-k n: sorts on the field specified by n -t: indicates that a specified character seperates the fields -m: merges input files that have been previously sorted -o: redirects output to a specified file -d: sorts in alphanumeric order -g: sorts by numeric (general) order -r: sorts in reverse order |
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Awk |
pattern-scanning and processing language -F: field seperator is a colon |
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diff |
compares two files and determines which lines differ.
-b: ignores blanks that repeat -B: does not compare for blank lines -i: ignores case -c: shows lines surrounding the line that differs (for context) -y: displays the differences side-by-side in columns |
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grep |
Selects lines or rows -i: ignores case -l: lists only file names -c: only counts the number of lines matching the pattern instead of showing them -r: searches through files under all subdirectories -n: includes the line number for each line found -v: displays only lines that don't contain the search pattern |
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pr |
formats a specified file -d: double spaces the output -h: customizes the header line -l n: sets the number of lines per page |
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sed |
specifies an editing command or a script file containing sed commands a\ appends text after a line p: displays lines d: deletes specified text s: substitutes specified text -e: specifies multiple commands on one line -n: indicates line numbers on which to work |
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sh |
executes a shell script
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tr |
translates characters
-d: deletes input characters found in string1 from the output -s: checks for sequences of string1 repeated consecutive times |
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uniq |
removes duplicate lines to create unique output
-u: outputs only the lines from the source file that are not duplicated -d: outputs one copy of each line that has a duplicate, and does not show unique lines. -i: ignores case -c: starts each line by showing the number of each instance
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wc |
counts the number of lines, bytes, or words in a file -c: counts the number of bytes or characters -l: counts the number of lines -w: counts the number of words |
