{"id":42,"date":"2022-03-04T15:11:17","date_gmt":"2022-03-04T20:11:17","guid":{"rendered":"https:\/\/pressbooks.library.ryerson.ca\/opsyshiraki\/chapter\/quick-reference-guide\/"},"modified":"2022-10-07T16:50:57","modified_gmt":"2022-10-07T20:50:57","slug":"quick-reference-guide","status":"publish","type":"chapter","link":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/chapter\/quick-reference-guide\/","title":{"raw":"Quick Reference Guide","rendered":"Quick Reference Guide"},"content":{"raw":"

Common Notations<\/h1>\r\nHere are some commonly used but easy-to-forget notations and syntax.\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
Notation<\/th>\r\nTypical usage with mini-example<\/th>\r\nWhere to get more info<\/th>\r\n<\/tr>\r\n<\/thead>\r\n
single quotes (')<\/td>\r\nCreates literal string protecting special characters.\r\n
grep 'Al Shaji' namelist<\/pre>\r\n<\/td>\r\n
Shell Variables<\/a><\/td>\r\n<\/tr>\r\n
double quotes (\")<\/td>\r\nLike single quotes but interprets $, \\ for variables.\r\n
echo \"Price: $value\"<\/pre>\r\n<\/td>\r\n
<\/td>\r\n<\/tr>\r\n
$(cmd)<\/td>\r\nCommand substitution.\u00a0 Runs cmd and substitutes output of cmd at position of call.\r\n
today=$(date)<\/pre>\r\n<\/td>\r\n
man bash\r\n\r\n <\/td>\r\n<\/tr>\r\n
set braces { }<\/td>\r\nFormal variable specification; substrings.\r\n
echo ${alpha:3:5}<\/pre>\r\n3 is offset (zero-based) and 5 is length<\/td>\r\n
<\/td>\r\n<\/tr>\r\n
double parentheses (( ))<\/td>\r\nArithmetic expression.\r\n
a=$(( $a + 1 ))<\/pre>\r\n<\/td>\r\n
man bash<\/td>\r\n<\/tr>\r\n
left square bracket [<\/td>\r\nSynonym for test command.\r\n
if [ $op = MR ]<\/pre>\r\nClosing right bracket is needed.<\/td>\r\n
man test<\/td>\r\n<\/tr>\r\n
[[ string =~ regex ]]<\/td>\r\nChecks to see if regular expression (regex) is contained in string\r\n\r\nExample\r\n\r\n[[ importing =~ port ]] will return TRUE\r\n\r\nCan be used with variables, too.\r\n\r\nExample\r\n\r\n[[ $title =~ $word ]] returns TRUE if $word is contained within $title<\/td>\r\nman bash<\/td>\r\n<\/tr>\r\n
Character classes in regular expressions\r\n\r\n[abc]<\/td>\r\nSquare brackets represent a single character pattern.\u00a0 Thus,\r\n\r\nr[aou]n matches ran, ron, or run.\r\n\r\n[Pp]olish matches Polish or polish<\/td>\r\nman regex.7\r\n\r\n <\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n

FAQs<\/h1>\r\nQ1a: How do make my script executable?\r\n\r\nQ1b: I'm getting an error message, \"-bash: .\/myscript: Permission denied\"\r\n\r\nA1: You need to issue the chmod command, either:\r\n
    \r\n \t
  • \r\n
    chmod 700 myscript<\/pre>\r\n<\/li>\r\n \t
  • \r\n
    chmod u+x myscript<\/pre>\r\n<\/li>\r\n<\/ul>\r\n ","rendered":"
    Common Notations<\/h1>\n
    Here are some commonly used but easy-to-forget notations and syntax.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n
    Notation<\/th>\nTypical usage with mini-example<\/th>\nWhere to get more info<\/th>\n<\/tr>\n<\/thead>\n
    single quotes (‘)<\/td>\nCreates literal string protecting special characters.<\/p>\n
    grep 'Al Shaji' namelist<\/pre>\n<\/td>\n
    		Shell Variables<\/a><\/td>\n<\/tr>\n
    double quotes (“)<\/td>\nLike single quotes but interprets $, \\ for variables.<\/p>\n
    echo \"Price: $value\"<\/pre>\n<\/td>\n
    		<\/td>\n<\/tr>\n
    $(cmd)<\/td>\nCommand substitution.\u00a0 Runs cmd and substitutes output of cmd at position of call.<\/p>\n
    today=$(date)<\/pre>\n<\/td>\n
    		man bash<\/p>\n
     <\/td>\n<\/tr>\n
    set braces { }<\/td>\nFormal variable specification; substrings.<\/p>\n
    echo ${alpha:3:5}<\/pre>\n
    3 is offset (zero-based) and 5 is length<\/td>\n
    		<\/td>\n<\/tr>\n
    double parentheses (( ))<\/td>\nArithmetic expression.<\/p>\n
    a=$(( $a + 1 ))<\/pre>\n<\/td>\n
    		man bash<\/td>\n<\/tr>\n
    left square bracket [<\/td>\nSynonym for test command.<\/p>\n
    if [ $op = MR ]<\/pre>\n
    Closing right bracket is needed.<\/td>\n
    		man test<\/td>\n<\/tr>\n
    [[ string =~ regex ]]<\/td>\nChecks to see if regular expression (regex) is contained in string<\/p>\n
    Example<\/p>\n
    [[ importing =~ port ]] will return TRUE<\/p>\n
    Can be used with variables, too.<\/p>\n
    Example<\/p>\n
    [[ $title =~ $word ]] returns TRUE if $word is contained within $title<\/td>\n
    		man bash<\/td>\n<\/tr>\n
    Character classes in regular expressions<\/p>\n
    [abc]<\/td>\n
    		Square brackets represent a single character pattern.\u00a0 Thus,<\/p>\n
    r[aou]n matches ran, ron, or run.<\/p>\n
    [Pp]olish matches Polish or polish<\/td>\n
    		man regex.7<\/p>\n
     <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    FAQs<\/h1>\n
    Q1a: How do make my script executable?<\/p>\n
    Q1b: I’m getting an error message, “-bash: .\/myscript: Permission denied”<\/p>\n
    A1: You need to issue the chmod command, either:<\/p>\n
      \n
    • \n
      chmod 700 myscript<\/pre>\n<\/li>\n
    • \n
      chmod u+x myscript<\/pre>\n<\/li>\n<\/ul>\n
       <\/p>\n","protected":false},"author":2,"menu_order":7,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-42","chapter","type-chapter","status-publish","hentry"],"part":23,"_links":{"self":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/pressbooks\/v2\/chapters\/42","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/wp\/v2\/users\/2"}],"version-history":[{"count":8,"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/pressbooks\/v2\/chapters\/42\/revisions"}],"predecessor-version":[{"id":75,"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/pressbooks\/v2\/chapters\/42\/revisions\/75"}],"part":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/pressbooks\/v2\/parts\/23"}],"metadata":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/pressbooks\/v2\/chapters\/42\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/wp\/v2\/media?parent=42"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/pressbooks\/v2\/chapter-type?post=42"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/wp\/v2\/contributor?post=42"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/opsyshiraki\/wp-json\/wp\/v2\/license?post=42"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}