Single command to create a file and set its permission
install -m 777 /dev/null filename.txt
shell
Creating files with some content with shell script
You can use a here document: cat <<EOF >filename first line second line third line EOF You can place several of these in the same script.
Write byte at address (hexedit/modify binary from the command line)
printf ‘\x31\xc0\xc3′ | dd of=test_blob bs=1 seek=100 count=3 conv=notrunc dd arguments: of | file to patch bs | 1 byte at a time please seek | go to position 100 (decimal) conv=notrunc | don’t truncate the output after the edit (which dd does by default) One Josh looking out for another 😉
Calling an executable program using awk
From the AWK man page: system(cmd) executes cmd and returns its exit status The GNU AWK manual also has a section that, in part, describes the system function and provides an example: system(“date | mail -s ‘awk run done’ root”)
Commandline hexdump with ASCII output?
hexdump -C does what you want. # hexdump -C /etc/passwd 00000000 72 6f 6f 74 3a 78 3a 30 3a 30 3a 72 6f 6f 74 3a |root:x:0:0:root:| 00000010 2f 72 6f 6f 74 3a 2f 62 69 6e 2f 62 61 73 68 0a |/root:/bin/bash.| 00000020 64 61 65 6d 6f 6e 3a 78 … Read more
How to input a path with a white space?
Use one of these threee variants: SOME_PATH=”/mnt/someProject/some path” SOME_PATH=’/mnt/someProject/some path’ SOME_PATH=/mnt/someProject/some\ path
Replace whole line when match found with sed
You can do it with either of these: sed ‘s/.*six.*/fault/’ file # check all lines sed ‘/six/s/.*/fault/’ file # matched lines -> then remove It gets the full line containing six and replaces it with fault. Example: $ cat file six asdf one two six one isix boo $ sed ‘s/.*six.*/fault/’ file fault asdf fault … Read more
How to download GitHub Release from private repo using command line
To download release file from private repo, you can use Personal access token which can be generated at settings/tokens with Full control of private repositories scope. Then download the asset with curl command (change with appropriate values): curl -vLJO -H ‘Authorization: token my_access_token’ ‘https://api.github.com/repos/:owner/:repo/releases/assets/:id’ or if you’re using an OAuth app, use: curl -u my_client_id:my_client_secret … Read more
How to comment out particular lines in a shell script
You can comment section of a script using a conditional. For example, the following script: DEBUG=false if ${DEBUG}; then echo 1 echo 2 echo 3 echo 4 echo 5 fi echo 6 echo 7 would output: 6 7 In order to uncomment the section of the code, you simply need to comment the variable: #DEBUG=false … Read more
Ansible playbook shell output
The debug module could really use some love, but at the moment the best you can do is use this: – hosts: all gather_facts: no tasks: – shell: ps -eo pcpu,user,args | sort -r -k1 | head -n5 register: ps – debug: var=ps.stdout_lines It gives an output like this: ok: [host1] => { “ps.stdout_lines”: [ … Read more