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Unix(cs252), unix commands - Coggle Diagram

- - - - splits file apart at places where the supplied pattern occurs
    - - is the pattern given here
        a regex?
        
        grep 'def' /usr/include/math.h
        
        def is a regex
    - - ( is a special character, must be inclosed in quotes when used as a regex in egrep
      - extended grep
      - more regex operations compared to grep
  - - - ex
        
        match any line containing 'd'
        
        grep d /usr/include/math.h
    - - ex
        
        match any line containing 'def'
        
        grep def /usr/include/math.h
        
        def == concatenation of regex + regex e + regex f
        which matches any substring which is a concatenation of substring d + substring e + substring f
        
        == grep (def)
  - - - obvious ex
      - special ex
    - - any set of chars within [] will match any string containing any one of those enclosed chars, unless the set beings with ^
        
        ex
        
        search for math(case insensitive)
        
        grep '[mM][aA][tT][hH]' /usr/include/math.h
        
        grep -i math /usr...
        
        ==
        
        range of characters can be abbreviated by a hyphen
        
        ex
        
        all lowercase letters
        
        [a-z]
        
        all upercase letters
        
        [A-Z]
        
        all letters
        
        [a-zA-Z]
  - - - execute dotest1
        
        ./dotest1
        
        in line 1 of each data file
        put the line
        #!./myprog
        then run the data files:
        ./test1.dat...
        
        using a single test file
        
        dotest1 test1.dat
        
        results of this command
        
        test1.dat fed to input of myprog
        
        output of myprog saved ti test1.dat.out
      - edit script such that when executing with a single file, it would go to a corresponding output
        
        #!/bin/sh
        ./myprog < $1 > $1.out
        
        $k == kth argument suppiled to the script
        
        given in file mcdonald, what would happen if it was ran as ./mcdonald cow moo
        
        And on that farm he had a cow
        EIEIO
        with a moo moo here,
        and a moo moo there
        
        prevent any of these arguments from interfering with the command
        
        "$k"
        
        prevents special characters from being read by the shell
        
        1 more item...
        
        what does the shell do?
    - - often used to point unix to a program that unix will use to process the remainder of the script
        
        using command
        
        #!pathtoprogram
        
        rest of program fed to that program's standard input
        
        types of programs that can be specified
        
        Any text file with execute permission
        
        most commonly, shells
        
        shells
        
        2 main families
        
        sh family
        
        2 more items...
        
        csh family
        
        2 more items...
        
        have control flow capabilities
        
        using status codes returned by programs indicating success(0)/failure(nonzero)
        
        2 more items...
        
        if
        
        loops(do & while)
        
        2 more items...
        
        operators
        
        input
        
        3 more items...
        
        output
        
        3 more items...
        
        |
        
        1 more item...
    - - grep --quiet [options] arguments
- - - - wildcard pattern is expanded before echo is run
      - ex
        
        find files with an extension
        
        echo /usr/include/.
        
        find header files containing pattern LARGE
        
        ignoring upper/lower case difference in files and pattern
        
        grep -i LARGE /usr/include/*.h
        
        case-Insensitive grep
        
        output files with match
        
        grep -l LARGE /usr/include/*.h
        
        output files with match, ignoring case difference in the pattern and the input files
        
        grep -i -l LARGE /usr/include/*.h
      - allowing this to work
        
        arguments in the shell are processed before the program is ran
- - - - cd
      - access command line
        
        run cmd
- - - - rmdir
    - - rmdir -r
  - - - windows equivalent
        
        del
- - - - u,g,o have rwx
        
        chmod 000
        
        ugo have no perms
- - - - chmod changes permissions for a specified file
      - umask sets default permissions for a file such that any newly created files within it will have those perms
      - both in octal, but numbers have reversed meanings
  - - - u,g,o have rwx
        
        umask 777
        
        ugo have no perms
- - - - echo $TERM
- - - - ls -a
    - - dir
- - - - this command:
        cards/.secret.txt
        does what?
        
        if that file does not already exist, it a hidden file is created
- - - - grep -v pattern
        
        filter .o and unix executables
        
        ls oldProject/* | grep -v '\.o' | grep '\.'
        
        copy every file that isnt an executable or object file into a new directory
        
        cp ls oldProject/* | grep -v '\.o' | grep '\.' newProject/
        
        windows requires files end in period, 3 letter extension,
        unix does not, text files, executables, and directories can be extensionless
        
        files in unix vs windows
        
        unix directories
        
        denotes a hidden file
        
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        3 user classes
        
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        3 forms of access to a file
        
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        2 kinds of file
        
        2 more items...