How to consider next line content with sed search and replace command?-CodePudding

I am trying to replace following pattern

  }

  if {[info exists env(PATH)]} {
     tcl::native_code " Message"
     tcl::native_code " Done"

with

    tcl_block

    if {[info exists env(PATH)]} {
       puts " Message"
       puts " Done"

with the help of sed/awk(preferable sed). But not sure how to consider the content of next line content while searching the pattern.

Please help! BR, Learner!!

CodePudding user response：

This might work for you (GNU sed):

sed '/^\s*}/{:a;N;/\n$/ba;/{\[info exists env(PATH)\]}/!{h;s/\(.*\)\n.*/\1/p;g;s/.*\n/\n/;D};s/}/tcl_block/}' file |
sed '/{\[info exists env(PATH)\]}/{:a;n;/\S/{s/tcl::native_code/puts/g;ba}}'

The solution is in two parts.

The first part, replaces a leading } by tcl_block if the next non-empty line contains {[info exists env(PATH)]}.

N.B. If the next non-empty line is does not match it is presented again as a possible match for }.

The second part, on matching {[info exists env(PATH)]}, replaces any occurrences of tcl::native_code by puts in any following lines up to the end of file or an empty line, which ever comes first.

If OP prefers to match from {[info exists env(PATH)]} to a closing } the second part can be simplified:

sed '/{\[info exists env(PATH)\]}/,/}/s/tcl::native_code/puts/g'

CodePudding user response：

You can try this sed with conditions mentioned in your comments.

sed '/\}/ {N;N;/if {\[info exists env(PATH)\]} {/ s/\}/tcl_block/};/tcl_block/ {N;N;/tcl/ s/tcl::native_code\|ntcl::native_code/puts/g}' $inputfile

Output

tcl_block

  if {[info exists env(PATH)]} {
     puts  "Message"
     puts  "Done"

If you have more tcl::native_code lines than the example data, then a complete recode may be needed but to handle it with this current code, add more N; lines to take into account for the substitution within the second condition.

sed '/\}/ {N;N;/if {\[info exists env(PATH)\]} {/ s/\}/tcl_block/};/tcl_block/ {N;N;N;/tcl/ s/tcl::native_code\|ntcl::native_code/puts/g}' $inputfile