Here’s one solution (assuming the input is a stream of valid JSON objects) and that you invoke jq with the -s option: map({ItemId: .Properties.ItmId}) # extract the ItmID values | group_by(.ItemId) # group by “ItemId” | map({ItemId: .[0].ItemId, Count: length}) # store the counts | .[] # convert to a stream A slightly more memory-efficient … Read more
You can use stat to get the file permissions, and parse them with another command to get the character you want. stat -c %A someFile Returns something like: -rw-rw-r– EDIT: Here you go: stat -c %A someFile | sed ‘s/…\(.\).\+/\1/’ Returns either – or x if the owner has execute. EDIT 2: For completion’s sake: … Read more
For bash, you can use the line: exec &>/dev/null This will direct all stdout and stderr to /dev/null from that point on. It uses the non-argument version of exec. Normally, something like exec xyzzy would replace the program in the current process with a new program but you can use this non-argument version to simply … Read more
You start a new process with Runtime.exec(command). Each process has a working directory. This is normally the directory in which the parent process was started, but you can change the directory in which your process is started. I would recommend to use ProcessBuilder ProcessBuilder pb = new ProcessBuilder(“ls”); pb.inheritIO(); pb.directory(new File(“bin”)); pb.start(); If you want … Read more
You can only do one substitution at a time, so you need to do it in two steps: newinet=${inet/inetnum: /} echo ${newinet/ – / }
You need to export shell variables in order to make them available to processes you execute in your shell. Compare the output of this command: FOO=bar; bash -c ‘echo $FOO’ with the output of this: export FOO=bar; bash -c ‘echo $FOO’
Simply append return 0 to the function to force a function to always exit successful. function a() { ls aaaaa 2>&1 return 0 } a echo $? # prints 0 If you wish to do it inline for any reason you can append || true to the command: ls aaaaa 2>&1 || true echo $? … Read more
It is the pipe symbol. It separates two programs on a command line (see Pipelines in the bash manual), and the standard output of the first program (on the LHS of the pipe) is connected to the standard input of the second program (on the RHS of the pipe). For example: who | wc -l … Read more
This is part of the rules of ~-expansion. It is clearly stated in the Bash manual that this expansion is not performed when the ~ is quoted. Workaround 1 Don’t quote the ~. file=~/path/to/file If you need to quote the rest of the filename: file=~/”path with spaces/to/file” (This is perfectly legal in a garden-variety shell.) … Read more