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Download Advanced Bash−Scripting Guide. An in−depth exploration of by Cooper M. PDF

By Cooper M.

This educational assumes no earlier wisdom of scripting or programming, yet progresses swiftly towards an intermediate/advanced point of guide ...all the whereas sneaking in little snippets of UNIX knowledge and lore. It serves as a textbook, a guide for self-study, and a reference and resource of information on shell scripting innovations. The workouts and heavily-commented examples invite lively reader participation, lower than the basis that the one option to particularly examine scripting is to put in writing scripts.

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Extra info for Advanced Bash−Scripting Guide. An in−depth exploration of the gentle art of shell scripting

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Operations and Related Topics 57 Advanced Bash−Scripting Guide exit 0 Integer variables in Bash are actually signed long (32−bit) integers, in the range of −2147483648 to 2147483647. An operation that takes a variable outside these limits will give an erroneous result. a=2147483646 echo "a = $a" let "a+=1" echo "a = $a" let "a+=1" echo "a = $a" # # # # # # a = 2147483646 Increment "a". a = 2147483647 increment "a" again, past the limit. a = −2147483648 ERROR (out of range) Bash does not understand floating point arithmetic.

Eq 0 ] && directorys=`pwd` || directorys=$@ #Setup the function linkchk to check the directory it is passed #for files that are links and don't exist, then print them quoted. #If one of the elements in the directory is a subdirectory then #send that send that subdirectory to the linkcheck function. ########## linkchk () { for element in $1/*; do [ −h "$element" −a ! −e "$element" ] && echo \"$element\" [ −d "$element" ] && linkchk $element # Of course, '−h' tests for symbolic link, '−d' for directory.

Chapter 5. Quoting 36 Advanced Bash−Scripting Guide (cd /source/directory && tar cf − . ) | \ (cd /dest/directory && tar xpvf −) # Repeating Alan Cox's directory tree copy command, # but split into two lines for increased legibility. # As an alternative: tar cf − −C /source/directory . | tar xpvf − −C /dest/directory # See note below. ) If a script line ends with a |, a pipe character, then a \, an escape, is not strictly necessary. It is, however, good programming practice to always escape the end of a line of code that continues to the following line.

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