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I am importing a file to my server using this command:
scp zumodo@shold:/test/test/test/server.py /test/test/test/test.py~/; I want to restart my server if the newly imported file test.py~ differs from the test.py that already exists. How would I do this using a shellscript?
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Use the diff command to compare text files. It can compare single files or the contents of directories. When the diff command is run on regular files, and when it compares text files in different directories, the diff command tells which lines must be changed in the files so that they match.
#1) cmp: This command is used to compare two files character by character. Example: Add write permission for user, group and others for file1. #2) comm: This command is used to compare two sorted files. One set of options allows selection of 'columns' to suppress.
If you all you want to know is whether two files are the same, use the -s (report identical files) option. You can use the -q (brief) option to get an equally terse statement about two files being different.
Bash Conditional Expressions File comparison If you want to compare two files byte by byte, use the cmp utility. To produce a human-readable list of differences between text files, use the diff utility.
if ! cmp test.py test.py~ >/dev/null 2>&1 then # restart service fi Breaking that down:
cmp test.py test.py~ returns true (0) if test.py and test.py~ are identical, else false (1). You can see this in man cmp.! inverts that result, so the if statement translates to "if test.py and test.py~ are different".>/dev/null 2>&1 send all output of cmp to null device, so you just get the true/false comparison result, without any unwanted noise on the console.
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