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UNIX Commands Ls – List Contents of a Directory UNIX Commands ls – list contents of a directory pwd – display current directory cd – change to directory (cd test) cp – copy file (cp from_file to_file) mv – move file (mv from_file to_file) rm – delete file (rm test1) mkdir – make directory (mkdir test) rmdir – remove directory (rmdir test) man – help for given command (man cp) cat – display contents of file more – display contents of file with page breaks (next page with Space key) head – display top of file tail – display end of file grep – search for pattern in file (grep “pattern“ test1) vi – edit file (more on this later) wc – count number of lines, words, characters in a file (wc -l file.txt) cut – cut out parts of file (cut -f 2 -d : file.txt) du – report disk usage (du -h) df – report file systems and their usage (df -h) chmod – change permissions of a file (chmod a+r file.txt) ln – create a link to a file (ln -s ~/bin/prog.exe prog1.exe) Wildcards: * - matches any number of letters incl. none ? - matches any single character [] - encloses set of characters that can match the single given position - used within [] denotes range of characters ~ - followed by user name = home directory (~mcuma) Command redirection: > redirect to a new file (cat test1 > test3) >> - append to a (new or existing) file (cat test2 >> test3) | - pipe – redirect command output to another command Vi basic reference i – insert I – insert at start of line a – append A – append at end of line o – enter insert mode on a new line r – replace single letter R – replace mode x – delete letter dd – delete line D – delete from cursor to end of line u – undo G – move to end of file #G – move to line # ^ - move to start of line $ - move to end of line ctrl-f – move page forward ctrl-b – move page back :w – save current file :w filename – save file to new file :q – quit vi :wq – save and quit :q! - quit without saving :w! - force save :n filename – open another file /pattern – search forward for pattern ? - search backward for pattern; subsequent entry of / or ? searches for next occurence of pattern :s/old_text/new_text – replace next occurence on current line :s/old_text/new_text/g – replace all occurence on current line :%s/old_text/new_text/g – replace all occurences in the whole file Scripting Loops foreach VAR ($VARLIST) … end while (condition) … end break – break out of the loop continue – skip to next loop iteration Conditions if (condition) then … else … endif switch (string) case pattern1: … breaksw default: commands... breaksw endsw Conditional expressions ==, !=, >, < ,&& ,|| - equal, not equal, larger, smaller than, and, or - like in C language !($?var) – true if variable does not exist =~ - if the right hand side matches a pattern, (i.e., similar to filename matching, with asterisks and question marks.) the condition is true. !~ - if the right hand side doesn't match a pattern, the condition is true. -d $var - true if the file is a directory. -e $var - true if the file exists. -f $var - true if the file is a file. (I.e., not a directory) -o $var - true if the file is owned by the user. -r $var - true if the user has read access. -w $var - true if the user has write access. -x $var - true if the user has execute access. -z $var - true if the file is zero-length. Shell variables variables are denoted with $ - echo $VAR strings defined by set – set VAR=(1 2 3 4) numbers defined by @ - @i = 1 conversion of string to number with expr - @i = `expr $number + 0`.
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