====== Bash / Shell ======

| ''<command> &'' | start and background |
| ''%%<command> &&%%'' | start and wait for success |
| ''>'' | write to new file (file reset is first operation)|
| ''%%>>%%'' | append to existing file |
| ''%%|%%'' | pipe output |

| ''diff'' | show differences |

====== Headline ======

| ''tar -tvf'' | List with details |
| ''tar czf data.tar.gz <folder/files>'' | compress file |
| ''tar -cjf archive.tar.bz2 <folder/files>'' | compress with bzip2 |
| ''tar -xzf data.tar.gz'' | decompress file | 
| ''tar -rvf archive.tar newfile'' | append to file |



====== Terminal Shortcuts ======

CTRL

| +a | Go to beginning of commandline | 
| +e | Go to end of command line |
| +u | Delete to line begin |
| +k | Delete to line end |
| +c | kill current process |
| +z | put current process in background |

===== Background processes =====

| ''jobs'' | list jobs |
| ''fg %#'' | move to foreground |
| ''bg'' | continue in background |
| ''kill %#'' or ''kill <pid>'' | kill process |
| ''kill -9 ..'' | terminate |


===== Filtering =====

| ''grep'' | Find strings in files |
| ''sort'' | Sort file |
| ''%%sort | uniq%%'', ''sort -u'' | Sort & remove duplicates |
| ''wc'' | word count |
| ''awk'' | don't ask |
| ''sed'' | replace characters in file |
| ''jq'', ''jq .'' | filter json |

===== Search =====


===== Others =====

| ''%%echo 'ABC=' | base64 -d%%'' | decode base64 |
| ''md5sum <file>'', ''sha256sum <file>'' | create checksum |

| visidata | search tabular/log files |



===== Log analysis =====

<source bash>
<nowiki>
sudo awk '{print $1" "$2" "$3, $4, $5, substr($0, index($0,$6))}' /var/log/auth.log | jq -R -c 'split(" ") | {timestamp: (.[0]+" "+.[1]+" "+.[2]), hostname: .[3], process: .[4], message: .[5:] | join(" ")}' > auth.json
</nowiki>
</source>