CODEWITHSUNDEEP
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lacrosse1991
lacrosse1991

Reputation: 3162

why wont sed read these variables properly?

I am currently trying to use sed to find and replace some text in a file, and for the terms that are being found/replaced, I am trying to use variables, but I cannot get them to work properly for some reason. The variables consist of c1-c9, which can be seen below:

    c1=$( echo "start time;project_start_time" )
    c2=$( echo "start_time;project_start_time" )
    c3=$( echo "end time;project_end_time" )
    c4=$( echo "end_time;project_end_time" )
    c5=$( echo "total time;project_total_time" )
    c6=$( echo "total_time;project_total_time" )
    c7=$( echo "project_id;project_ID" )
    c8=$( echo "status;project_status" )
    c9=$( echo "client_id;client_ID" )
    c10=$( echo "employee_id;employee_ID" )
    c11=$( echo "employee_name;employee_name" )
    c12=$( echo "date created;date_created" )
    c13=$( echo "date_created;date_created" )

and the code that contains the sed part is:

 while [ "$countc" -le 13 ]; do
                    real_string=$( eval echo "\$c$countc" | cut -d ';' -f 2 )
                    nc_string=$( eval echo "\$c$countc" | cut -d ';' -f 1 )
                    sed -e "s/$nc_string/$real_string/gI" phasef/"$count"p.csv #> phasef/"$count".csv
                    countc=$(( $countc + 1 ))
            done

(there is more code to the script, but it is irrelevant) When I run the script, if i tell it to output real_string/nc_string as the while loop moves along, the variables are correctly outputted, real_string/nc_string variables are actually being defined correctly, but I am not sure why sed is not reading them correctly. If anyone could point out what I am doing wrong I would really appreciate it as I have been trying to figure this out for a few hours now, thanks!

Upvotes: 0

Views: 179

Answers (3)

glenn jackman
glenn jackman

Reputation: 246774

I think @anishsane probably has the right answer. I just want to offer some notes about your code. If you're using bash, take advantage of some of bash's features:

1) just assign a string instead of spawning a subshell to echo the string:

c1="start time;project_start_time"

(unless the echo is just a placeholder here for some more complicated process

2) use an array instead of numerically-indexed variables

c=(
     "start time;project_start_time"
     "start_time;project_start_time"
     "end time;project_end_time"
     "end_time;project_end_time"
     "total time;project_total_time"
     "total_time;project_total_time"
     "project_id;project_ID"
     "status;project_status"
     "client_id;client_ID"
     "employee_id;employee_ID"
     "employee_name;employee_name"
     "date created;date_created"
     "date_created;date_created" 
)

3) split the strings with read and IFS and avoid eval nastiness:

for (( countc=1; countc <= ${#c[@]}; countc++ )); do
    IFS=';' read nc_string real_string <<< "${c[countc]}"
    # ...
done

Upvotes: 3

anishsane
anishsane

Reputation: 20980

I checked the echo for "s/$nc_string/$real_string/gI" & it is expanding the variables properly. Please let us know, the input file contents.

I suspect that, highlited part in below line has some issue.

sed -e "s/$nc_string/$real_string/gI" phasef/"$count"p.csv > phasef/"$count".csv

If you want to replace all pairs in input file (phasef/${count}p.csv) & save to output file (phasef/$count.csv), use below code:

cp phasef/"$count"p.csv phasef/"$count".csv
while [ "$countc" -le 13 ]; do
    real_string=$( eval echo "\$c$countc" | cut -d ';' -f 2 )
    nc_string=$( eval echo "\$c$countc" | cut -d ';' -f 1 )
    sed -i -e "s/$nc_string/$real_string/gI"  phasef/"$count".csv
    countc=$(( $countc + 1 ))
done

Note the -i in sed line.

Upvotes: 2

Olaf Dietsche
Olaf Dietsche

Reputation: 74018

You have a typo in the sed line. Change

sed -e "s/$nc_string/$real_string/gI" phasef/"$count"p.csv

to

sed -e "s/$nc_string/$real_string/gI" phasef/"$countc"p.csv

Upvotes: 0

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