esh(1) - f29

1ESH(1)                                                                  ESH(1)
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NAME

6       esh - simple template system based on shell
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SYNOPSIS

9       esh [-d] [-o output] [-s shell] [--] file [variable ...]
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11       esh <-h | -V>
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DESCRIPTION

14       esh (embedded shell) is a templating engine for evaluating shell
15       commands embedded in arbitrary templates. It’s like ERB (Embedded RuBy)
16       for shell, intended to be used for templating configuration files.
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18       esh converts template file, or stdin if file is “-”, into a sequence of
19       shell commands. Commands between <% and %> tags are passed as-is,
20       everything else is escaped and prefixed with printf command. These
21       commands are eventually evaluated using shell (unless -d is specified).
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OPTIONS

24       -d
25           Don’t evaluate template, just dump a shell script.
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27       -o file
28           Output file or “-” for STDOUT. Defaults to “-”.
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30       -s shell
31           Command name or path of the shell to use for template evaluation.
32           It must not contain spaces. Defaults to “/bin/sh”.
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34       -h
35           Show help message and exit.
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37       -V
38           Print version and exit.
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ENVIRONMENT

41       esh may be configured using the following environment variables:
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43       ESH_AWK
44           Command name of path of the awk program to use. It must not contain
45           spaces. Defaults to “awk”.
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47       ESH_SHELL
48           The same as -s shell.
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EXIT STATUS

51       esh exits with the exit status of shell or awk.
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TEMPLATE SYNTAX

54       ESH has two tags for shell code, a tag for comments, and a way to
55       escape tag delimiters.
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57       <% commands %>
58           Executes the commands and replaces this tag with its output on
59           stdout.
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61       <%= values %>
62           Executes printf '%s ' with the values as arguments and replaces
63           this tag with the output (without trailing white space). values are
64           not quoted or escaped, so all shell substitutions are applied.
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66       <%# comment %>
67           Removed from the final output.
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69       -%>
70           May be used instead of %>. It trims the following line break if
71           used at the end of line, otherwise has no trimming effect.
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73       <%%
74           A literal <% when used outside of the above tags.
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76       %%>
77           A literal %> when used inside of the above tags.
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79       Opening and closing tag may not be at the same line.
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81       Text outside a tag becomes literal text, but it is subject to any
82       tagged shell code surrounding it. For example, text surrounded by a
83       tagged if statement only appears in the output if the condition is
84       true.
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EXAMPLES

87       nginx.conf.esh
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89           http {
90               access_log <%= $logs_dir/access.log %> main;
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92               resolver <%= $(sed -En 's/^nameserver ([^#]+)/\1/p' /etc/resolv.conf) %>;
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94               <% if nginx -V 2>&amp;1 | grep -q lua-nginx-module; then -%>
95               lua_package_path '<%= $(pkg-config --variable=INSTALL_LMOD lua) %>/?.lua';
96               <% fi -%>
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98               <%# The rest of the config is omitted %>
99           }
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101       To generate the resulting configuration file run:
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103           esh -o nginx.conf nginx.conf.esh logs_dir=/var/log/nginx
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AUTHORS

106       esh’s author is Jakub Jirutka.
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REPORTING BUGS

109       Report bugs to the project’s issue tracker at <https://github.com/
110       jirutka/esh/issues>.
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