进入命令行环境以后,一般就已经打开Bash 了。如果你的 Shell 不是 Bash,可以输入bash命令启动Bash。 $ bash 退出Bash 环境,可以使用exit命令,也可以同时按下Ctrl + d。 $ exit Bash 的基本用法就是在命令行输入各种命令,非常直观。作为练习,可以试着输入pwd命令。按下回车键,就会显示当前所在的目录。 $ pwd /...
grep: This command searches text using patterns. -e "pattern1" -e "pattern2": This part of the command specifies multiple patterns to search for. The -e option allows specifying multiple patterns. "pattern1" and "pattern2": These are the patterns to search for. In this case, the comman...
This option can be used to protect a pattern beginning with “-”.-f FILE, --file=FILE Obtain patterns from FILE, one per line. If this option is used multiple times or is combined with the -e, searchforall patterns given. The emptyfilecontains zero patterns, and therefore matches nothi...
True randomness is unpredictable and lacks any patterns. It’s typically derived from physical phenomena, like atmospheric noise or radioactive decay. However, computers, being deterministic machines, find it challenging to generate truly random numbers. That’s where pseudo-randomness comes in. Pseudo...
In this example, the script checks the user’s input against three patterns: ‘apple’, ‘banana’, and ‘cherry’. If the user enters ‘banana’, the script prints ‘You entered banana’. If the user enters something other than these three fruits, the script prints ‘You did not enter...
Log Analysis:Scan and analyze log files for specific patterns or anomalies. Automated Software Installation:Install software packages on multiple machines without manual intervention. Tips and Best Practices Start with a Shebang (#!/bin/bash):This tells the system to use the Bash shell to execute...
Like in other programming languages, an array in bash is a variable that allows you to refer to multiple values. In bash, arrays are also zero-based, that is, the first element in an array has index 0. When dealing with arrays, we should be aware of the special environment variableIFS...
If a file name matched by a pathname expansion pattern also matches one of the patterns in GLOBIGNORE, it is removed from the list of matches. HISTCONTROL A colon-separated list of values controlling how commands are saved on the history list. If the list of values includes ignorespace, ...
The | sign is used for separating multiple patterns, and the ) operator terminates a pattern list. The commands for the first match are executed. * is the pattern for anything else that doesn't match the defined patterns. Each block of commands should be divided with the ;; operator....
# curl to servers matching multiple PATTERNs provided via `knife node list` to check their health/build status # usage: kcurla PATTERN local fqdn_srvr_list if knife_env_set; then knife_node_list=`mktemp /tmp/knl.XXXX` /usr/bin/knife node list -c $KNIFERB > $knife_node_list...